ICSE – Grade 8 – Physics – Ch 03 – QA

Questions & Answers

ICSE - Grade - 8

Subject: Physics

Chapter - 03 - Force and Pressure

Types of Questions

MCQ

  1. Which of the following is a unit of force?
    a) Joule
    b) Watt
     c) Newton
     d) Pascal
     Ans: c) Newton

 

  1. What does a force cause?
    a) Change in colour
    b) Change in smell
     c) Change in motion or shape
     d) Change in temperature
     Ans: c) Change in motion or shape

 

  1. Which of the following is a scalar quantity?
    a) Force
    b) Thrust
     c) Pressure
     d) Acceleration
     Ans: c) Pressure

 

  1. The turning effect of force is called:
    a) Pressure
    b) Thrust
     c) Motion
     d) Moment of force
     Ans: d) Moment of force

 

  1. 1 newton =
    a) 1 kg × 1 m
    b) 1 kg × 1 m/s²
     c) 1 m/s²
     d) 1 kg/m²
     Ans: b) 1 kg × 1 m/s²

 

  1. Which factor increases the turning effect of a force?
    a) Force applied only
    b) Distance from pivot only
     c) Both force and perpendicular distance
     d) Surface area
     Ans: c) Both force and perpendicular distance

 

  1. SI unit of moment of force is:
    a) Newton
    b) Joule
     c) Newton-metre
     d) Pascal
     Ans: c) Newton-metre

 

  1. A door is easier to open when pushed:
    a) Near the hinge
    b) At the middle
     c) At the edge far from hinge
     d) Does not matter
     Ans: c) At the edge far from hinge

 

  1. A force of 10 N acts at a distance of 0.5 m from the pivot. Moment of force is:
    a) 5 N·m
    b) 20 N·m
     c) 10 N·m
     d) 0.5 N·m
     Ans: a) 5 N·m

 

  1. Thrust is defined as:
    a) Force applied parallel to surface
    b) Force applied in any direction
     c) Force applied normally (perpendicular) to a surface
     d) Weight of the object
     Ans: c) Force applied normally (perpendicular) to a surface

 

  1. SI unit of thrust is:
    a) Pascal
    b) Newton
     c) Newton-metre
     d) Kilogram
     Ans: b) Newton

 

  1. Pressure is equal to:
    a) Force × Area
    b) Force / Area
     c) Area / Force
     d) Area × Volume
     Ans: b) Force / Area

 

  1. SI unit of pressure is:
    a) Joule
    b) Newton
     c) Pascal
     d) Kilogram
     Ans: c) Pascal

 

  1. Which of the following will exert the most pressure?
    a) 50 N force over 5 m²
    b) 50 N force over 10 m²
     c) 50 N force over 1 m²
     d) 50 N force over 100 m²
     Ans: c) 50 N force over 1 m²

 

  1. Pressure increases with:
    a) Increase in area
    b) Decrease in force
     c) Decrease in area
     d) Increase in volume
     Ans: c) Decrease in area

 

  1. The pressure on a surface is less when:
    a) The area is small
    b) The force is more
     c) The area is large
     d) None of these
     Ans: c) The area is large

 

  1. Liquid pressure depends on:
    a) Volume only
    b) Height of column and density
     c) Shape of vessel
     d) Surface area
     Ans: b) Height of column and density

 

  1. The pressure inside a liquid increases with:
    a) Increase in temperature
    b) Increase in height
     c) Decrease in density
     d) Increase in surface area
     Ans: b) Increase in height

 

  1. A hydraulic press works on the principle of:
    a) Gravity
    b) Atmospheric pressure
     c) Liquid pressure
     d) Magnetic pressure
     Ans: c) Liquid pressure

 

  1. Atmospheric pressure is measured using a:
    a) Thermometer
    b) Barometer
     c) Manometer
     d) Hygrometer
     Ans: b) Barometer

 

  1. Atmospheric pressure at sea level is:
    a) 1 Pa
    b) 10⁵ Pa
     c) 1.013 × 10⁵ Pa
     d) 100 Pa
     Ans: c) 1.013 × 10⁵ Pa

 

  1. Which unit is used for measuring atmospheric pressure in laboratory?
    a) Metre
    b) Pascal
     c) Centimetre of mercury
     d) Kelvin
     Ans: c) Centimetre of mercury

 

  1. Which of the following shows atmospheric pressure?
    a) Balloon bursts when over-inflated
    b) Water flows from higher to lower level
     c) Weight increases with height
     d) Light travels in straight line
     Ans: a) Balloon bursts when over-inflated

 

  1. Which of these tools uses pressure in daily life?
    a) Spoon
    b) Knife
     c) Plate
     d) Book
     Ans: b) Knife

 

  1. Sharp knives cut better due to:
    a) Greater area
    b) Smaller area
     c) Greater mass
     d) Less density
     Ans: b) Smaller area

 

  1. Wide tyres are used in tractors because:
    a) They look good
    b) Increase speed
     c) Reduce pressure on ground
     d) Increase friction
     Ans: c) Reduce pressure on ground

 

  1. Camels walk easily on sand because they have:
    a) Sharp claws
    b) Heavy body
     c) Broad feet
     d) Long legs
     Ans: c) Broad feet

 

  1. A man exerts more pressure when:
    a) Standing
    b) Sitting
     c) Lying down
     d) Sleeping
     Ans: a) Standing

 

  1. Suction cups stick to wall due to:
    a) Gravitational force
    b) Friction
     c) Atmospheric pressure
     d) Magnetic force
     Ans: c) Atmospheric pressure

 

  1. Which of the following acts in all directions?
    a) Force
    b) Pressure
     c) Liquid pressure
     d) All of these
     Ans: d) All of these

 

  1. A gas exerts pressure because:
    a) Its molecules are at rest
    b) Its molecules collide with container walls
     c) It has mass
     d) It expands
     Ans: b) Its molecules collide with container walls

 

  1. The greater the height of a liquid column:
    a) Lesser is the pressure
    b) Greater is the pressure
     c) No change in pressure
     d) Only volume increases
     Ans: b) Greater is the pressure

 

  1. Which factor does not affect pressure in liquids?
    a) Density
    b) Colour
     c) Height
     d) Nature of liquid
     Ans: b) Colour

 

  1. A force is applied at the center of a wheel. The turning effect will be:
    a) Maximum
    b) Zero
     c) Infinite
     d) Cannot say
     Ans: b) Zero

 

  1. Unit of pressure in CGS system is:
    a) Dyne
    b) Dyne/cm²
     c) Erg
     d) Pascal
     Ans: b) Dyne/cm²

 

  1. A 100 N force over an area of 2 m² gives pressure of:
    a) 100 Pa
    b) 50 Pa
     c) 200 Pa
     d) 10 Pa
     Ans: b) 50 Pa

 

  1. In pressure = thrust/area, pressure increases when:
    a) Area increases
    b) Area decreases
     c) Thrust decreases
     d) Mass decreases
     Ans: b) Area decreases

 

  1. Which instrument demonstrates atmospheric pressure?
    a) Lever
    b) Barometer
     c) Pulley
     d) Screw
     Ans: b) Barometer

 

  1. Which of the following quantities is a vector?
    a) Pressure
    b) Area
     c) Thrust
     d) Temperature
     Ans: c) Thrust

 

  1. In a dam, the wall is thicker at the bottom because:
    a) Water is heavier
    b) Pressure increases with depth
     c) Wall needs strength
     d) Force is more
     Ans: b) Pressure increases with depth

 

  1. SI unit of moment of force is same as that of:
    a) Work
    b) Force
     c) Energy
     d) Torque
     Ans: d) Torque

 

  1. Thrust per unit area is called:
    a) Force
    b) Moment
     c) Pressure
     d) Work
     Ans: c) Pressure

 

  1. Which factor determines moment of force?
    a) Speed
    b) Distance from pivot
     c) Pressure
     d) Time
     Ans: b) Distance from pivot

 

  1. A barometer is used to measure:
    a) Temperature
    b) Force
     c) Atmospheric pressure
     d) Liquid pressure
     Ans: c) Atmospheric pressure

 

  1. A pressure of 200 Pa acts over 0.5 m². Find thrust.
    a) 400 N
    b) 100 N
     c) 200 N
     d) 50 N
     Ans: a) 100 N

 

  1. Why are tanks provided with outlets at bottom?
    a) Easy cleaning
    b) More liquid pressure
     c) Better filling
     d) Easier to reach
     Ans: b) More liquid pressure

 

  1. The downward force acting on an object is its:
    a) Area
    b) Volume
     c) Thrust
     d) Pressure
     Ans: c) Thrust

 

  1. Pressure depends on which two factors?
    a) Volume and time
    b) Thrust and area
     c) Mass and speed
     d) Temperature and energy
     Ans: b) Thrust and area

 

  1. At higher altitudes, atmospheric pressure:
    a) Increases
    b) Decreases
     c) Remains same
     d) Doubles
     Ans: b) Decreases

 

  1. Which physical quantity is measured in N/m²?
    a) Force
    b) Pressure
     c) Energy
     d) Mass
     Ans: b) Pressure

Fill in the Blanks

  1. A force can change the __________ of a body.

Ans: state of motion



  1. The SI unit of force is __________.

Ans: newton



  1. Force is a __________ quantity.

Ans: vector



  1. The force acting perpendicular to a surface is called __________.

Ans: thrust



  1. The SI unit of thrust is __________.

Ans: newton



  1. The pressure is defined as __________ per unit area.

Ans: thrust



  1. The SI unit of pressure is __________.

Ans: pascal



  1. 1 pascal = 1 __________ per square metre.

Ans: newton



  1. When area decreases, pressure __________.

Ans: increases



  1. Pressure is a __________ quantity.

Ans: scalar



  1. The turning effect of a force is known as the __________.

Ans: moment of force



  1. Moment of force = Force × __________ from pivot.

Ans: perpendicular distance



  1. The SI unit of moment of force is __________.

Ans: newton-metre



  1. The force applied on a door is more effective when applied __________ from the hinge.

Ans: farther



  1. A spanner works by applying a force to produce a __________.

Ans: turning effect



  1. A sharp knife cuts better because it has __________ area of contact.

Ans: smaller



  1. A camel can walk easily on sand due to its __________ feet.

Ans: broad



  1. In pressure = thrust / area, pressure increases when area is __________.

Ans: decreased



  1. The pressure inside a liquid increases with __________.

Ans: depth



  1. Liquid pressure also depends on the __________ of the liquid.

Ans: density



  1. A dam is thicker at the bottom because pressure __________ with depth.

Ans: increases



  1. Liquid pressure at a point acts in __________ directions.

Ans: all



  1. The instrument used to measure atmospheric pressure is a __________.

Ans: barometer



  1. The atmospheric pressure at sea level is __________ Pa.

Ans: 1.013 × 10⁵



  1. The standard atmospheric pressure is equal to __________ cm of mercury.

Ans: 76



  1. A suction cup sticks to a wall due to __________ pressure.

Ans: atmospheric



  1. Drinking through a straw is possible due to __________ pressure.

Ans: atmospheric



  1. The pressure exerted by gases and liquids is due to __________ of molecules.

Ans: collisions



  1. A barometer uses __________ to measure atmospheric pressure.

Ans: mercury



  1. The SI unit of pressure in liquids is the same as in gases, i.e., __________.

Ans: pascal



  1. Force is a __________ or a pull.

Ans: push



  1. Pressure depends on two factors: thrust and __________.

Ans: area



  1. The weight of an object acts as a __________ on the surface.

Ans: thrust



  1. Pressure = __________ / Area.

Ans: Thrust



  1. When a person stands, pressure on the ground is __________ than when he lies down.

Ans: more



  1. In liquids, pressure acts equally in __________ directions.

Ans: all



  1. Wide tyres of tractors reduce the __________ on the ground.

Ans: pressure



  1. A knife cuts due to high pressure from a __________ area.

Ans: small



  1. The thrust acting on a unit area is called __________.

Ans: pressure



  1. A force applied at a greater distance from the pivot produces a __________ moment.

Ans: larger



  1. The perpendicular distance between the force and pivot is called __________ arm.

Ans: moment



  1. A man exerts more pressure on the ground when he is __________.

Ans: standing



  1. The pressure of a liquid increases with increase in __________.

Ans: height



  1. A pressure of 1 pascal is equal to a thrust of 1 N on an area of __________ m².

Ans: 1



  1. The area of contact and thrust together determine the __________ on a surface.

Ans: pressure



  1. A force of 5 N applied at a distance of 2 m from pivot gives a moment of __________ N·m.

Ans: 10



  1. The height of the mercury column in a barometer at sea level is __________ cm.

Ans: 76



  1. Liquids exert pressure because their molecules are in constant __________.

Ans: motion



  1. At higher altitudes, atmospheric pressure __________.

Ans: decreases



  1. Atmospheric pressure is caused by the __________ of air above us.

Ans: weight

Name the Following

  1. Name the unit of force in SI system.
     Ans: newton


  2. Name the unit of pressure in SI system.
     Ans: pascal


  3. Name the force that acts perpendicular to a surface.
     Ans: thrust


  4. Name the quantity defined as force per unit area.
     Ans: pressure


  5. Name the unit of moment of force in SI.
     Ans: newton-metre


  6. Name the instrument used to measure atmospheric pressure.
     Ans: barometer


  7. Name the scientist after whom the unit of pressure (pascal) is named.
     Ans: Blaise Pascal


  8. Name two physical factors on which liquid pressure depends.
     Ans: height of liquid column, density of liquid


  9. Name the quantity which causes rotation in a body.
     Ans: moment of force


  10. Name the fixed point about which a body rotates.
     Ans: pivot


  11. Name the pressure exerted by liquids.
     Ans: liquid pressure


  12. Name the pressure exerted by the atmosphere.
     Ans: atmospheric pressure


  13. Name the fluid which is used in a barometer.
     Ans: mercury


  14. Name a situation where thrust is increased by reducing area.
     Ans: cutting with a knife


  15. Name the force that causes turning effect in a lever.
     Ans: effort


  16. Name the effect of a force which changes the state of motion.
     Ans: dynamic effect


  17. Name the effect of a force which changes the shape or size.
     Ans: deforming effect


  18. Name one machine that works based on turning effect of force.
     Ans: spanner


  19. Name the quantity which increases when the area is decreased and thrust remains same.
     Ans: pressure


  20. Name a real-life example where pressure decreases by increasing area.
     Ans: camel’s broad feet


  21. Name a scalar physical quantity related to thrust.
     Ans: pressure


  22. Name a vector quantity related to pressure.
     Ans: thrust


  23. Name the direction in which liquid pressure acts.
     Ans: all directions


  24. Name the pressure that enables us to drink using a straw.
     Ans: atmospheric pressure


  25. Name the component of pressure responsible for bursting of balloons.
     Ans: atmospheric pressure


  26. Name a device where high pressure is applied over a small area to cut objects.
     Ans: knife


  27. Name the reason why dams are made thicker at the base.
     Ans: increasing liquid pressure with depth


  28. Name a condition where person applies least pressure on ground.
     Ans: lying down


  29. Name the pressure measured in cm of mercury.
     Ans: atmospheric pressure


  30. Name the law or principle used in hydraulic press.
     Ans: Pascal’s law


  31. Name the unit of pressure in CGS system.
     Ans: dyne/cm²


  32. Name the factor which directly increases moment of force.
     Ans: force or perpendicular distance


  33. Name one device that makes use of atmospheric pressure to function.
     Ans: suction cup


  34. Name the physical quantity calculated by multiplying force and distance.
     Ans: moment of force


  35. Name the relation: Pressure = ______ / Area
     Ans: thrust


  36. Name the physical quantity that remains constant at every point in a fluid at same level.
     Ans: pressure


  37. Name a daily life example of turning effect of force.
     Ans: opening a door


  38. Name a machine that applies a force at a distance from pivot.
     Ans: crowbar


  39. Name the force due to air that prevents mercury from falling in barometer.
     Ans: atmospheric pressure


  40. Name the quantity which has the same unit as torque.
     Ans: moment of force


  41. Name the reason why pointed heels damage soft floors.
     Ans: high pressure due to small area


  42. Name the effect observed when water comes out faster from lower holes of a tank.
     Ans: increase in liquid pressure with depth


  43. Name the two factors which determine pressure on a surface.
     Ans: thrust and area


  44. Name the phenomenon responsible for barometric readings.
     Ans: atmospheric pressure


  45. Name one factor that does not affect liquid pressure.
     Ans: shape of container


  46. Name the quantity measured in N/m².
     Ans: pressure


  47. Name the condition when a body changes its state of motion.
     Ans: unbalanced force


  48. Name the type of pressure acting uniformly in all directions at a point in fluid.
     Ans: hydrostatic pressure


  49. Name the value of standard atmospheric pressure in pascals.
     Ans: 1.013 × 10⁵ Pa


  50. Name the pressure that decreases with altitude.
     Ans: atmospheric pressure

Answer in One Word

  1. What is the SI unit of force?
     Ans: newton


  2. What is the SI unit of pressure?
     Ans: pascal


  3. Which force acts normally on a surface?
     Ans: thrust


  4. What do we call force per unit area?
     Ans: pressure


  5. What is the SI unit of moment of force?
     Ans: newton-metre


  6. Which instrument measures atmospheric pressure?
     Ans: barometer


  7. What is the standard atmospheric pressure in cm of Hg?
     Ans: 76


  8. Which fluid is used in a barometer?
     Ans: mercury


  9. What is the turning effect of a force called?
     Ans: moment


  10. What is the point of rotation called?
     Ans: pivot


  11. What is the physical quantity that changes with area and thrust?
     Ans: pressure


  12. Which quantity increases when area decreases for same thrust?
     Ans: pressure


  13. What type of quantity is pressure – scalar or vector?
     Ans: scalar


  14. What type of quantity is thrust – scalar or vector?
     Ans: vector


  15. What do we call the force that causes rotation?
     Ans: moment


  16. What is 1 N equal to in terms of mass and acceleration?
     Ans: 1 kg·m/s²


  17. What kind of force acts uniformly in all directions in a liquid?
     Ans: liquid pressure


  18. Which force enables us to drink with a straw?
     Ans: atmospheric


  19. What is used to demonstrate atmospheric pressure in a lab?
     Ans: barometer


  20. What is the thrust of air on a surface known as?
     Ans: atmospheric


  21. What is the SI unit of thrust?
     Ans: newton


  22. What is the force acting on a unit area called?
     Ans: pressure


  23. Which physical quantity causes deformation in a body?
     Ans: force


  24. What is the quantity that depends on both force and distance from pivot?
     Ans: moment


  25. Which part of the door provides maximum turning effect?
     Ans: edge


  26. What is the relation between pressure and area (direct/inverse)?
     Ans: inverse


  27. Which factor increases pressure in liquids – height or shape?
     Ans: height


  28. What type of pressure do gases exert?
     Ans: atmospheric


  29. Which component of pressure is responsible for suction cup sticking?
     Ans: atmospheric


  30. What is the value of standard atmospheric pressure in Pa?
     Ans: 1.013 × 10⁵


  31. What is the CGS unit of pressure?
     Ans: dyne/cm²


  32. What is the pressure exerted by air above us called?
     Ans: atmospheric


  33. What increases when force is applied farther from pivot?
     Ans: moment


  34. What reduces pressure exerted by a man when lying down?
     Ans: area


  35. What is the pressure exerted by a liquid on its container?
     Ans: liquid


  36. What is the shape of a container’s effect on pressure in liquid?
     Ans: none


  37. Which factor causes balloon to burst when overfilled?
     Ans: pressure


  38. What causes a dam to have thicker walls at the bottom?
     Ans: pressure


  39. Which device increases thrust without increasing pressure?
     Ans: hydraulic press


  40. What quantity is measured in N/m²?
     Ans: pressure


  41. What is another name for N/m²?
     Ans: pascal


  42. What is the physical quantity measured by barometer?
     Ans: pressure


  43. What enables a knife to cut better – high or low pressure?
     Ans: high


  44. What is applied when you tighten a bolt using a spanner?
     Ans: moment


  45. What is the direction of liquid pressure at a point?
     Ans: all


  46. What is the force responsible for barometric readings?
     Ans: atmospheric


  47. What reduces pressure for constant thrust?
     Ans: area


  48. What is needed for a force to produce rotation?
     Ans: pivot


  49. What is 1 pascal equal to in base SI units?
     Ans: N/m²


  50. What increases with both depth and density in liquids?
     Ans: pressure

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Find the Odd Man Out

  1. Newton, Pascal, Dyne, Kilogram
     Ans: Kilogram
     Explanation: Kilogram is a unit of mass, others are units of force or pressure.


  2. Pressure, Thrust, Force, Area
     Ans: Area
     Explanation: Area is not a force; others are related to applied force.


  3. Mercury, Water, Oil, Copper
     Ans: Copper
     Explanation: Copper is a solid; others are liquids.


  4. Barometer, Thermometer, Manometer, Aneroid Barometer
     Ans: Thermometer
     Explanation: Thermometer measures temperature; others measure pressure.


  5. Thrust, Pressure, Density, Moment
     Ans: Density
     Explanation: Density is a property of matter, not directly related to force or pressure.


  6. Force, Mass, Thrust, Weight
     Ans: Mass
     Explanation: Mass is scalar; others are vector forces.


  7. Door, Spanner, Tap, Balloon
     Ans: Balloon
     Explanation: Balloon is not a device showing turning effect of force.


  8. Pascal, Newton, Joule, Kelvin
     Ans: Kelvin
     Explanation: Kelvin is unit of temperature; others are mechanical units.


  9. Pivot, Effort, Load, Temperature
     Ans: Temperature
     Explanation: Temperature is unrelated to the turning effect or force systems.


  10. Lying down, Standing, Sitting, Running
     Ans: Running
     Explanation: Running involves motion; others describe static postures affecting pressure.


  11. Suction pump, Straw, Barometer, Thermometer
     Ans: Thermometer
     Explanation: Thermometer doesn’t demonstrate atmospheric pressure.


  12. Knife, Pin, Broad Shoe, Needle
     Ans: Broad Shoe
     Explanation: Broad shoe reduces pressure; others increase pressure.


  13. Area, Height, Density, Depth
     Ans: Area
     Explanation: Area does not affect liquid pressure; others do.


  14. Moment, Pressure, Force, Power
     Ans: Power
     Explanation: Power is rate of doing work; others are force-related quantities.


  15. Suction Cup, Barometer, Spanner, Straw
     Ans: Spanner
     Explanation: Spanner is based on turning effect, not atmospheric pressure.


  16. Pivot, Effort, Load, Length
     Ans: Length
     Explanation: Length is not a force component in levers.


  17. Hydraulic press, Syringe, Vacuum Cleaner, Knife
     Ans: Knife
     Explanation: Knife does not function based on liquid or atmospheric pressure.


  18. Pressure, Thrust, Energy, Force
     Ans: Energy
     Explanation: Energy is not directly involved in force/pressure definition.


  19. Barometer, Manometer, Aneroid barometer, Thermos
     Ans: Thermos
     Explanation: Thermos is not a pressure-measuring instrument.


  20. Distance, Force, Pivot, Shape
     Ans: Shape
     Explanation: Shape doesn’t affect turning effect; others do.


  21. Pascal, N/m², Newton, Bar
     Ans: Newton
     Explanation: Newton is unit of force; others are pressure units.


  22. Gravity, Friction, Magnetic, Density
     Ans: Density
     Explanation: Density is a material property, not a force.


  23. Newton-metre, Newton, Dyne, Joule
     Ans: Joule
     Explanation: Joule is unit of energy; others relate to force.


  24. Beaker, Test Tube, Barometer, Flask
     Ans: Barometer
     Explanation: Barometer measures pressure; others are containers.


  25. Gas, Liquid, Air, Wood
     Ans: Wood
     Explanation: Wood is solid; others are fluids.


  26. Thrust, Temperature, Force, Pressure
     Ans: Temperature
     Explanation: Temperature is not a mechanical quantity.


  27. Mercury, Iron, Water, Oil
     Ans: Iron
     Explanation: Iron is solid; others are liquids.


  28. Camel foot, Needle, Sharp pin, Knife
     Ans: Camel foot
     Explanation: Camel foot reduces pressure; others increase pressure.


  29. Kilogram, Metre, Second, Pascal
     Ans: Pascal
     Explanation: Pascal is derived unit; others are base SI units.


  30. Volume, Pressure, Area, Thrust
     Ans: Volume
     Explanation: Volume doesn’t directly affect pressure calculations.


  31. 1 N, 1 Pa, 1 J, 1 kg·m/s²
     Ans: 1 J
     Explanation: Joule is unit of energy; others are force/pressure.


  32. Dam, Tank, Barrel, Tap
     Ans: Tap
     Explanation: Tap controls flow; others store liquid under pressure.


  33. Knife, Axe, Plough, Table
     Ans: Table
     Explanation: Table doesn’t demonstrate pressure concept.


  34. Mercury barometer, Aneroid barometer, Thermometer, U-tube manometer
     Ans: Thermometer
     Explanation: Thermometer does not measure pressure.


  35. Water, Oil, Air, Aluminium
     Ans: Aluminium
     Explanation: Aluminium is solid; others are fluids.


  36. Area, Depth, Density, Colour
     Ans: Colour
     Explanation: Colour does not affect pressure.


  37. Needle, Pin, Knife, Pillow
     Ans: Pillow
     Explanation: Pillow is not designed to increase pressure.


  38. Pressure, Volume, Temperature, Distance from pivot
     Ans: Temperature
     Explanation: Temperature doesn’t affect moment of force.


  39. Thrust, Pressure, Momentum, Force
     Ans: Momentum
     Explanation: Momentum is mass × velocity; others relate to force application.


  40. Spanner, Wrench, Screwdriver, Knife
     Ans: Knife
     Explanation: Knife doesn’t use turning effect.


  41. Suction cup, Vacuum pump, Tap, Syringe
     Ans: Tap
     Explanation: Tap doesn’t demonstrate atmospheric pressure.


  42. Force, Pressure, Speed, Thrust
     Ans: Speed
     Explanation: Speed is a kinematic quantity, not related to pressure.


  43. Lever, Pulley, Barometer, Wedge
     Ans: Barometer
     Explanation: Barometer is not a simple machine.


  44. Force, Mass, Acceleration, Temperature
     Ans: Temperature
     Explanation: Temperature is not involved in Newton’s second law.


  45. Shape, Density, Height, Depth
     Ans: Shape
     Explanation: Shape does not affect liquid pressure.


  46. Manometer, Thermometer, Barometer, Aneroid
     Ans: Thermometer
     Explanation: Others measure pressure; thermometer measures temperature.


  47. Friction, Gravity, Temperature, Magnetic
     Ans: Temperature
     Explanation: Others are forces; temperature is not.


  48. Syringe, Barometer, Spanner, Straw
     Ans: Spanner
     Explanation: Spanner is not based on atmospheric pressure.


  49. Handle, Pivot, Force, Mercury
     Ans: Mercury
     Explanation: Mercury is not part of a lever system.


  50. Kilogram, Newton, Pascal, Celsius
     Ans: Celsius
     Explanation: Celsius measures temperature; others are mechanical units.

Match the Pair

Set 1: Match the Pairs

Column A

  1. Force
  2. Pressure
  3. Thrust
  4. Moment of Force
  5. Unit of Pressure

Column B
 a) Newton
 b) Turning effect
 c) N/m²
 d) Perpendicular force on surface
 e) Force per unit area

Answers:
 1–a
 2–e
 3–d
 4–b
 5–c


Set 2: Match the Pairs

Column A

  1. Barometer
  2. Standard atmospheric pressure
  3. Unit of force
  4. SI unit of moment
  5. Pressure in liquid

Column B
 a) Acts in all directions
 b) 76 cm Hg
 c) Newton
 d) Newton-metre
 e) Measures air pressure

Answers:
 1–e
 2–b
 3–c
 4–d
 5–a


Set 3: Match the Pairs

Column A

  1. Knife edge
  2. Broad feet of camel
  3. More pressure
  4. Less pressure
  5. Pressure increases

Column B
 a) With increased thrust
 b) Small area of contact
 c) On sand
 d) With reduced area
 e) With increased area

Answers:
 1–b
 2–c
 3–d
 4–e
 5–a


Set 4: Match the Pairs

Column A

  1. Thrust
  2. Pascal
  3. Turning effect
  4. Pivot
  5. Spanner

Column B
 a) SI unit of pressure
 b) Point of rotation
 c) Force acting normally
 d) Used to rotate bolts
 e) Moment of force

Answers:
 1–c
 2–a
 3–e
 4–b
 5–d



Set 5: Match the Pairs

Column A

  1. Mercury
  2. Straw
  3. Suction cup
  4. Barometer
  5. Atmospheric pressure

Column B
 a) Demonstrates pressure
 b) Used in barometer
 c) Measures pressure
 d) Present around us
 e) Enables drinking

Answers:
 1–b
 2–e
 3–a
 4–c
 5–d



Set 6: Match the Pairs

Column A

  1. Pressure depends on
  2. Pressure increases
  3. Area increases
  4. Pressure
  5. Unit of thrust

Column B
 a) N/m²
 b) With increase in thrust
 c) Newton
 d) Thrust and area
 e) Pressure decreases

Answers:
 1–d
 2–b
 3–e
 4–a
 5–c



Set 7: Match the Pairs

Column A

  1. Greater depth in liquid
  2. Height of mercury column
  3. Air pressure
  4. Open door
  5. Small area

Column B
 a) Applies more pressure
 b) Makes turning easier
 c) Exerts pressure
 d) 76 cm at sea level
 e) Increases pressure

Answers:
 1–e
 2–d
 3–c
 4–b
 5–a



Set 8: Match the Pairs

Column A

  1. Pressure in liquids
  2. Knife
  3. Weight of air
  4. Balloon burst
  5. Force

Column B
 a) Push or pull
 b) Sharp edge
 c) Atmospheric pressure
 d) Acts in all directions
 e) High internal pressure

Answers:
 1–d
 2–b
 3–c
 4–e
 5–a



Set 9: Match the Pairs

Column A

  1. 1 Pascal
  2. Pressure increases with
  3. Spanner works on
  4. Less area
  5. Dams are thicker at

Column B
 a) Increases pressure
 b) 1 N/m²
 c) Turning effect
 d) Bottom
 e) More depth

Answers:
 1–b
 2–e
 3–c
 4–a
 5–d



Set 10: Match the Pairs

Column A

  1. Suction effect
  2. Knife cut
  3. Hydraulic press
  4. Thrust
  5. Pressure in gas

Column B
 a) Acts in all directions
 b) Due to atmospheric pressure
 c) Depends on collisions
 d) Force perpendicularly applied
 e) Due to high pressure

Answers:
 1–b
 2–e
 3–a
 4–d
 5–c

Short Answer Questions  

  1. What is force?
     Ans: Force is a push or pull that changes or tends to change the state of rest or motion of a body.


  2. Define thrust.
     Ans: Thrust is the force acting normally on a surface.


  3. Define pressure.
     Ans: Pressure is the thrust acting per unit area of a surface.


  4. State the SI unit of force.
     Ans: The SI unit of force is newton (N).


  5. State the SI unit of pressure.
     Ans: The SI unit of pressure is pascal (Pa).


  6. Write the formula for pressure.
     Ans: Pressure = Thrust / Area


  7. What is 1 pascal?
     Ans: 1 pascal is the pressure exerted when a thrust of 1 newton acts on an area of 1 m².


  8. What is the moment of a force?
     Ans: Moment of a force is the turning effect of a force about a point.


  9. Write the formula for the moment of a force.
     Ans: Moment of force = Force × Perpendicular distance from the pivot.


  10. State the SI unit of moment of force.
     Ans: The SI unit of moment of force is newton-metre (N·m).


  11. What is the condition for maximum turning effect of a force?
     Ans: The turning effect is maximum when the force is applied perpendicular to the pivot.


  12. Name the point about which a body rotates.
     Ans: Pivot


  13. Give one example of a tool based on turning effect of force.
     Ans: Spanner


  14. Why is the handle of a door fixed far from the hinge?
     Ans: To increase the turning effect by increasing the perpendicular distance from the pivot.


  15. Name the physical quantity that increases with thrust and decreases with area.
     Ans: Pressure


  16. What is the effect on pressure when area decreases?
     Ans: Pressure increases when area decreases.


  17. Why do sharp objects cut better?
     Ans: Because they exert more pressure due to smaller contact area.


  18. Why do camels have broad feet?
     Ans: To reduce pressure on the sand and prevent sinking.


  19. State one factor on which liquid pressure depends.
     Ans: Liquid pressure depends on the height of the liquid column.


  20. Does the shape of the container affect liquid pressure?
     Ans: No, the shape of the container does not affect liquid pressure.


  21. In which direction does liquid pressure act?
     Ans: Liquid pressure acts in all directions.


  22. Where is liquid pressure highest in a tank?
     Ans: At the bottom of the tank.


  23. What is atmospheric pressure?
     Ans: Atmospheric pressure is the pressure exerted by the weight of air on the Earth’s surface.


  24. Name the instrument used to measure atmospheric pressure.
     Ans: Barometer


  25. What is the standard atmospheric pressure at sea level in pascal?
     Ans: 1.013 × 10⁵ pascal


  26. What is the standard atmospheric pressure in cm of mercury?
     Ans: 76 cm of mercury


  27. Why does the barometer reading fall on a mountain?
     Ans: Because atmospheric pressure decreases with altitude.


  28. Why does a suction cup stick to a wall?
     Ans: Due to the atmospheric pressure acting on it.


  29. Why can we drink through a straw?
     Ans: Because atmospheric pressure pushes the liquid up when we reduce air pressure inside the straw.


  30. What is the relation between pressure and area for a given thrust?
     Ans: Pressure is inversely proportional to area.


  31. Why are dams built thicker at the base?
     Ans: To withstand greater liquid pressure at greater depth.


  32. Which is more — pressure at greater depth or lesser depth?
     Ans: Pressure is more at greater depth.


  33. State the unit of pressure in CGS system.
     Ans: Dyne/cm²


  34. What is the thrust on a 5 m² surface when pressure is 100 Pa?
     Ans: Thrust = 500 N


  35. What happens to pressure if area is doubled and thrust remains same?
     Ans: Pressure is halved.


  36. Define 1 newton.
     Ans: 1 newton is the force that produces an acceleration of 1 m/s² in a body of mass 1 kg.


  37. What happens to the moment when distance from pivot increases?
     Ans: Moment increases.


  38. What is the thrust on a surface when area = 2 m² and pressure = 50 Pa?
     Ans: Thrust = 100 N


  39. Why are sharp nails easier to hammer into a wall?
     Ans: Because they exert more pressure due to their pointed ends.


  40. Why are wide tyres used in tractors?
     Ans: To reduce pressure on the soft ground.


  41. Give an example showing atmospheric pressure in daily life.
     Ans: Drinking water through a straw.


  42. What is the pressure at the bottom of a liquid column of height h and density ρ?
     Ans: Pressure = h × ρ × g


  43. What type of pressure does a barometer measure?
     Ans: Atmospheric pressure


  44. Which physical quantity has unit N/m²?
     Ans: Pressure


  45. Which force holds the mercury in a barometer tube?
     Ans: Atmospheric pressure


  46. What is the reading of a barometer in a vacuum?
     Ans: Zero


  47. What is the purpose of using mercury in a barometer instead of water?
     Ans: Mercury is denser, so its column height is shorter.


  48. What is the effect of gravity on atmospheric pressure?
     Ans: Gravity causes the air to exert pressure.


  49. Why is a dam wall curved inward?
     Ans: To better resist the water pressure.


  50. What happens to atmospheric pressure when altitude increases?
     Ans: Atmospheric pressure decreases.

Puzzles

  1. I am a force acting perpendicularly on a surface. What am I?
     Ans: Thrust


  2. I am a push or a pull. I change the motion of a body. What am I?
     Ans: Force


  3. I am the unit used to measure pressure. You can find me in the SI system. What am I?
     Ans: Pascal


  4. I am the pressure unit, and I am equal to 1 N/m². What am I?
     Ans: Pascal


  5. You see me in action when you rotate a spanner. What effect am I?
     Ans: Moment of force


  6. I decrease when the area of contact increases, for the same thrust. What am I?
     Ans: Pressure


  7. I am the fixed point about which rotation happens. Who am I?
     Ans: Pivot


  8. I rise in a glass tube when the atmospheric pressure increases. What am I?
     Ans: Mercury in a barometer


  9. My value at sea level is 76 cm of Hg. What am I?
     Ans: Atmospheric pressure


  10. You can’t see me, but I push in all directions. What invisible force am I?
     Ans: Atmospheric pressure


  11. I make it hard to walk on sand with high heels. What am I?
     Ans: High pressure


  12. My moment increases if you apply me farther from the pivot. What am I?
     Ans: Force


  13. I help you drink juice through a straw. What hidden helper am I?
     Ans: Atmospheric pressure


  14. You measure me with a barometer. Who am I?
     Ans: Atmospheric pressure


  15. I am high at sea level and low in the mountains. What am I?
     Ans: Atmospheric pressure


  16. I let you turn a door easily when applied far from the hinge. What am I?
     Ans: Moment of force


  17. I make water gush out faster from the bottom of a tank. What pressure am I?
     Ans: Liquid pressure


  18. You stand up; I increase. You lie down; I decrease. What am I?
     Ans: Pressure


  19. I am the product of force and perpendicular distance. What quantity am I?
     Ans: Moment of force


  20. You stepped on me with pointed heels. I hurt you! What am I?
     Ans: Pressure


  21. The pressure at my bottom is more than at my top. What container am I?
     Ans: Water tank


  22. I am in syringes, straws, and suction cups. What force am I?
     Ans: Atmospheric pressure


  23. You applied force on a large area. I remained small. What am I?
     Ans: Pressure


  24. You hammer me into wood. I go in easily because I am sharp. What am I?
     Ans: Nail


  25. My SI unit is N·m. You see me when you twist a nut. What am I?
     Ans: Moment of force


  26. I am used to split wood and have a sharp edge. What tool am I?
     Ans: Wedge


  27. I keep the mercury in a barometer suspended. What unseen force am I?
     Ans: Atmospheric pressure


  28. You find me in a hydraulic press. I transmit force through a liquid. What principle am I?
     Ans: Pascal’s law


  29. I decrease with height and make breathing difficult in high mountains. What am I?
     Ans: Atmospheric pressure


  30. The smaller the area, the more I increase. What am I?
     Ans: Pressure


  31. I am a type of pressure caused by liquids. Who am I?
     Ans: Liquid pressure


  32. You push me at the end of a spanner, and I create a turning force. What am I?
     Ans: Force


  33. I am measured in newtons. I cause change in motion. What am I?
     Ans: Force


  34. I am the reason why water pressure is higher at the base of a dam. What am I?
     Ans: Depth


  35. I’m a unit, but not for pressure. I measure mass. What am I?
     Ans: Kilogram


  36. You apply me with your foot on the ground. I support your weight. What am I?
     Ans: Thrust


  37. I act equally in all directions in a liquid. What kind of pressure am I?
     Ans: Liquid pressure


  38. I am the reason why mercury doesn’t fall from an inverted test tube. What am I?
     Ans: Atmospheric pressure


  39. I am applied perpendicularly and measured in newtons. What am I?
     Ans: Thrust


  40. I become zero when no force is applied. What am I?
     Ans: Pressure


  41. I am the force per unit area. What physical quantity am I?
     Ans: Pressure


  42. I go up when you increase thrust and reduce area. What am I?
     Ans: Pressure


  43. I allow machines to lift heavy loads using liquid pressure. What system am I?
     Ans: Hydraulic system


  44. I am the effect you feel when someone punches you. What force am I?
     Ans: Thrust


  45. I act on your body every second of the day, from above. What invisible force am I?
     Ans: Atmospheric pressure


  46. I am used to measure air pressure. I contain mercury. What instrument am I?
     Ans: Barometer


  47. I am responsible for more pressure on narrow chair legs than wide ones. What am I?
     Ans: Smaller area


  48. I make balloons expand when blown into. What am I?
     Ans: Air pressure


  49. I am pressure applied by gases due to constant collisions. What kind of pressure am I?
     Ans: Gas pressure


  50. I act upward, perpendicular to a surface, and resist weight. What am I?
     Ans: Normal thrust

Difference Between:

  1. Difference between Force and Pressure
    Force is a physical quantity that causes an object to move, stop, or change its shape. It is a vector quantity and is measured in newtons (N). Pressure, on the other hand, is the force applied per unit area. It is a scalar quantity and measured in pascals (Pa). While force causes the effect, pressure determines how concentrated that force is over a surface.

 

  1. Difference between Thrust and Pressure
    Thrust is the total force acting perpendicular (normally) on a surface. It is a vector quantity and its SI unit is newton (N). Pressure is defined as thrust per unit area. It is a scalar quantity and its SI unit is pascal (Pa). Hence, pressure depends on both thrust and the area over which it is applied.

 

  1. Difference between Balanced and Unbalanced Forces
    Balanced forces are equal in magnitude and opposite in direction, and they do not change the state of motion of an object. The net force in this case is zero. Unbalanced forces, however, result in a change in motion or acceleration of an object since the forces do not cancel out and the net force is not zero.

 

  1. Difference between Contact Force and Non-contact Force
    Contact force is a force that acts between objects that are physically touching each other, like friction or muscular force. Non-contact force acts at a distance without any physical contact, like gravitational force, magnetic force, or electrostatic force.

 

  1. Difference between Push and Pull
    A push is a force that moves an object away from the source of the force. A pull is a force that brings the object closer to the source of the force. Both are types of applied forces but differ in direction and effect.

 

  1. Difference between Mass and Weight
    Mass is the quantity of matter in an object and remains constant everywhere. Its SI unit is kilogram (kg). Weight is the force with which the Earth attracts an object toward itself and depends on the local gravitational field. Its SI unit is newton (N).

 

  1. Difference between Liquid Pressure and Atmospheric Pressure
    Liquid pressure is the pressure exerted by a liquid at a given depth and depends on the liquid’s density and the height of the column. Atmospheric pressure is the pressure exerted by the air in the Earth’s atmosphere and decreases with altitude. Liquid pressure acts in all directions in the liquid, while atmospheric pressure acts in all directions around an object.

 

  1. Difference between Pressure and Stress
    Pressure is an external force applied per unit area on a surface, while stress is an internal restoring force per unit area developed within a material due to applied force. Both are measured in pascals, but pressure is applied externally and stress develops internally.

 

  1. Difference between Uniform and Non-uniform Pressure
    Uniform pressure refers to pressure that is the same at all points in a medium or surface, such as in a stationary liquid at the same depth. Non-uniform pressure varies from point to point, such as pressure caused by an uneven force or in turbulent fluids.

 

  1. Difference between Scalar and Vector Quantities
    Scalar quantities have only magnitude and no direction. Examples include mass, speed, and pressure. Vector quantities have both magnitude and direction. Examples include force, velocity, and displacement.

 

  1. Difference between Moment and Force
    Force is a push or pull acting on a body and can move it linearly. Moment is the turning effect of a force about a fixed point (pivot) and is calculated as the product of force and perpendicular distance from the pivot. While force causes translation, moment causes rotation.

 

  1. Difference between High Pressure and Low Pressure Regions
    A high-pressure region is an area where the pressure is greater than its surroundings, and fluids tend to move away from it. A low-pressure region is an area with lower pressure, which tends to attract fluids from surrounding areas. This difference causes fluid movement.

 

  1. Difference between Solid Pressure and Liquid Pressure
    Solid pressure is exerted by solids when force is applied over an area and acts only in the direction of the force. Liquid pressure is exerted by fluids and acts equally in all directions at a given depth. Liquid pressure increases with depth, unlike solid pressure.

 

  1. Difference between Frictional Force and Normal Force
    Frictional force acts parallel to the contact surface and opposes motion. Normal force acts perpendicular to the surface and supports the weight of an object placed on it. Friction depends on the nature of surfaces; normal force depends on the object’s weight.

 

  1. Difference between Mercury and Water as Barometric Fluids
    Mercury has high density and requires a shorter column (~76 cm) to measure atmospheric pressure. Water has low density and would require a much taller column (~10.3 m) for the same purpose. Mercury is also less volatile, making it more suitable for barometers.

 

  1. Difference between Atmospheric Pressure and Vacuum
    Atmospheric pressure is the pressure exerted by the Earth’s atmosphere, typically measured at sea level as 1.013 × 10⁵ Pa. A vacuum is a space completely devoid of matter, including air, and thus has no atmospheric pressure. Objects behave differently in both conditions.

 

  1. Difference between Area and Volume
    Area is the measure of the extent of a surface and is expressed in square units (e.g., m²). Volume is the measure of the space occupied by an object and is expressed in cubic units (e.g., m³). Area is two-dimensional, while volume is three-dimensional.

 

  1. Difference between Pressure and Density
    Pressure is the force exerted per unit area and is measured in pascals. Density is the mass per unit volume of a substance and is measured in kg/m³. While pressure is related to applied force, density is related to the compactness of matter in a material.

 

  1. Difference between Gravity and Pressure
    Gravity is a natural force that attracts objects toward the center of the Earth. Pressure is the result of a force acting over an area. Gravity causes weight, while pressure can be due to liquids, gases, or solids acting on surfaces.

 

  1. Difference between Turning Force and Linear Force
    Turning force, or moment, causes an object to rotate about a fixed point. Linear force causes an object to move in a straight line. Turning force depends on both the magnitude of the force and the distance from the pivot, while linear force depends only on the magnitude and direction.

Assertion and Reason

Instructions:
 A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
 B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
 C) Assertion is true, but Reason is false.
 D) Assertion is false, but Reason is true.


  1. Assertion: Force can change the shape of a body.
     Reason: Force is a scalar quantity.
     Ans: C


  2. Assertion: Thrust is a vector quantity.
     Reason: It has both magnitude and direction.
     Ans: A


  3. Assertion: Pressure is a vector quantity.
     Reason: Pressure is force acting per unit area.
     Ans: C


  4. Assertion: A sharp knife cuts better than a blunt one.
     Reason: A sharp knife exerts more pressure due to smaller contact area.
     Ans: A


  5. Assertion: Broad feet of camels help them walk easily on sand.
     Reason: Broad feet increase pressure on the ground.
     Ans: C


  6. Assertion: A man lying on the ground exerts more pressure than when he is standing.
     Reason: Pressure increases with increase in surface area.
     Ans: D


  7. Assertion: A spanner is used to open nuts easily.
     Reason: It increases the perpendicular distance from the pivot.
     Ans: A


  8. Assertion: Thrust is the force acting tangentially to a surface.
     Reason: Thrust acts normally to a surface.
     Ans: D


  9. Assertion: The SI unit of moment of force is newton.
     Reason: Moment of force = Force × Distance.
     Ans: C


  10. Assertion: Pressure is directly proportional to thrust.
     Reason: Pressure = Thrust / Area.
     Ans: A


  11. Assertion: Pressure in a liquid increases with depth.
     Reason: Deeper points have more weight of the liquid column above.
     Ans: A


  12. Assertion: Dams are built thicker at the base.
     Reason: Liquid pressure decreases with depth.
     Ans: C


  13. Assertion: Atmospheric pressure acts in all directions.
     Reason: Air molecules exert equal force in all directions.
     Ans: A


  14. Assertion: Mercury is used in barometers.
     Reason: Mercury is transparent and less dense.
     Ans: C


  15. Assertion: The unit of pressure is newton.
     Reason: Pressure is defined as force per unit area.
     Ans: C


  16. Assertion: A crowbar can lift heavy loads.
     Reason: It multiplies force using turning effect.
     Ans: A


  17. Assertion: A barometer is used to measure force.
     Reason: Barometer measures atmospheric pressure.
     Ans: C


  18. Assertion: Pressure in a fluid is independent of its shape.
     Reason: It depends on height and density.
     Ans: A


  19. Assertion: Pressure in liquids is uniform at same depth.
     Reason: Pressure acts equally in all directions.
     Ans: A


  20. Assertion: Atmospheric pressure decreases with height.
     Reason: Air becomes less dense at higher altitudes.
     Ans: A


  21. Assertion: Pressure increases when force decreases.
     Reason: Pressure = Force × Area.
     Ans: D


  22. Assertion: Mercury level in barometer falls on a mountain.
     Reason: Atmospheric pressure is lower at high altitudes.
     Ans: A


  23. Assertion: Pressure is measured in N·m.
     Reason: Pressure = Force / Area.
     Ans: C


  24. Assertion: A spanner works best when force is applied near the nut.
     Reason: Smaller distance increases moment of force.
     Ans: D


  25. Assertion: The moment of force depends on perpendicular distance from pivot.
     Reason: More distance causes more turning effect.
     Ans: A


  26. Assertion: Liquids exert pressure in upward direction only.
     Reason: Liquids are heavier than solids.
     Ans: D


  27. Assertion: Liquid pressure acts only downwards.
     Reason: Gravity acts downward.
     Ans: D


  28. Assertion: The unit pascal is used to measure pressure.
     Reason: 1 Pa = 1 N/m².
     Ans: A


  29. Assertion: A balloon expands when inflated.
     Reason: Internal air pressure exceeds atmospheric pressure.
     Ans: A


  30. Assertion: More liquid in a tank means more pressure at the bottom.
     Reason: Pressure increases with height of liquid column.
     Ans: A


  31. Assertion: The weight of air exerts atmospheric pressure.
     Reason: Air has mass.
     Ans: A


  32. Assertion: A heavier person applies more pressure when standing.
     Reason: Pressure depends only on area.
     Ans: C


  33. Assertion: Force is required to change the motion of a body.
     Reason: Force can change the state of motion.
     Ans: A


  34. Assertion: Pressure increases with increase in area.
     Reason: Pressure = Force / Area.
     Ans: D


  35. Assertion: The handle of a door is fixed far from the hinge.
     Reason: To increase turning effect by increasing distance.
     Ans: A


  36. Assertion: Atmospheric pressure is a result of air molecules colliding with surfaces.
     Reason: Air has kinetic energy and moves randomly.
     Ans: A


  37. Assertion: Pressure at the bottom of the ocean is less than on surface.
     Reason: Pressure in liquid decreases with depth.
     Ans: D


  38. Assertion: A needle pierces cloth easily.
     Reason: It has a sharp tip and small area.
     Ans: A


  39. Assertion: A person sitting exerts more pressure than standing.
     Reason: Area of contact increases while sitting.
     Ans: D


  40. Assertion: The pressure of liquids depends on the shape of container.
     Reason: Shape changes surface area.
     Ans: D


  41. Assertion: Suction cups fall off in vacuum.
     Reason: Atmospheric pressure is absent in vacuum.
     Ans: A


  42. Assertion: Pressure in liquids is always constant.
     Reason: Liquid is incompressible.
     Ans: C


  43. Assertion: We feel pain when stepped on by someone wearing high heels.
     Reason: Smaller area increases pressure.
     Ans: A


  44. Assertion: Air pressure cannot crush steel containers.
     Reason: Atmospheric pressure is very low.
     Ans: C


  45. Assertion: Air pressure can hold water in an inverted glass with card.
     Reason: Atmospheric pressure acts upwards.
     Ans: A


  46. Assertion: Increasing area decreases pressure.
     Reason: Pressure is inversely proportional to area.
     Ans: A


  47. Assertion: A barometer shows higher reading at sea level.
     Reason: Atmospheric pressure is highest at sea level.
     Ans: A


  48. Assertion: Spanner is a machine showing atmospheric pressure.
     Reason: It rotates about pivot.
     Ans: D


  49. Assertion: Water tank outlets are placed at bottom.
     Reason: Pressure is highest at the bottom of the tank.
     Ans: A


  50. Assertion: Force can produce motion.
     Reason: A balanced force changes motion.
     Ans: C

True or False

  1. Force is a push or pull that can change the state of motion of a body.
     Ans: True


  2. Thrust is the force acting parallel to a surface.
     Ans: False


  3. Pressure is defined as thrust per unit area.
     Ans: True


  4. The SI unit of force is joule.
     Ans: False


  5. 1 newton = 1 kg·m/s²
     Ans: True


  6. Pressure increases when thrust increases.
     Ans: True


  7. Pressure is directly proportional to area.
     Ans: False


  8. A sharp knife exerts less pressure than a blunt knife.
     Ans: False


  9. A man exerts more pressure when lying down than when standing.
     Ans: False


  10. A spanner works by producing moment of force.
     Ans: True


  11. The moment of a force is defined as force multiplied by speed.
     Ans: False


  12. The SI unit of pressure is pascal.
     Ans: True


  13. Pascal = N/m²
     Ans: True


  14. Greater the area, greater the pressure for a constant thrust.
     Ans: False


  15. Thrust is a scalar quantity.
     Ans: False


  16. Pressure in a liquid increases with depth.
     Ans: True


  17. The pressure in a fluid depends on the shape of its container.
     Ans: False


  18. Liquids exert pressure in one direction only.
     Ans: False


  19. Atmospheric pressure acts only downward.
     Ans: False


  20. Atmospheric pressure decreases with altitude.
     Ans: True


  21. Mercury is used in a barometer because it is opaque.
     Ans: False


  22. The standard atmospheric pressure at sea level is 76 cm of mercury.
     Ans: True


  23. A suction cup sticks to a wall due to gravitational force.
     Ans: False


  24. The barometer is used to measure temperature.
     Ans: False


  25. Thrust is the same as pressure.
     Ans: False


  26. A wide foundation of a building reduces pressure on the ground.
     Ans: True


  27. Pressure is a vector quantity.
     Ans: False


  28. The moment of force is also called torque.
     Ans: True


  29. The handle of a door is fixed far from the hinge to reduce pressure.
     Ans: False


  30. Pressure = Force / Area
     Ans: True


  31. Mercury column in a barometer is taller at sea level.
     Ans: True


  32. The value of 1 atmosphere is 1.013 × 10⁵ Pa.
     Ans: True


  33. More depth means less liquid pressure.
     Ans: False


  34. More density means more liquid pressure.
     Ans: True


  35. The weight of air creates atmospheric pressure.
     Ans: True


  36. A barometer uses alcohol instead of mercury.
     Ans: False


  37. The turning effect depends only on the force applied.
     Ans: False


  38. The unit of moment of force is N·m.
     Ans: True


  39. A straw works due to suction and atmospheric pressure.
     Ans: True


  40. The effect of thrust is more when the area is large.
     Ans: False


  41. Suction pump works on atmospheric pressure.
     Ans: True


  42. If area is doubled, pressure becomes half for same force.
     Ans: True


  43. The thrust is always applied horizontally.
     Ans: False


  44. The force of gravity causes atmospheric pressure.
     Ans: True


  45. Liquid pressure depends on the type of container.
     Ans: False


  46. The reading of a barometer remains unchanged with altitude.
     Ans: False


  47. Pressure applied on a fluid in a closed container is transmitted equally in all directions.
     Ans: True


  48. Force has only magnitude.
     Ans: False


  49. Pressure and thrust are numerically equal always.
     Ans: False


  50. A larger perpendicular distance from pivot increases the moment.
     Ans: True

Long Answer Questions

  1. Define force. Mention its effects with examples.
    Ans: Force is a physical quantity that causes or tends to cause motion in a body or changes the state of motion or the shape of the body. It is a push or a pull.
    Effects of force:
     (i) It can change the speed of a moving body. Example: Applying brakes on a moving bicycle slows it down.
     (ii) It can stop a moving object. Example: A goalkeeper stops a football.
     (iii) It can change the direction of a moving object. Example: A tennis player hits a ball to change its direction.
     (iv) It can change the shape and size of a body. Example: Pressing a rubber ball changes its shape.

 

  1. What is thrust? How is it different from pressure?
    Ans: Thrust is the force acting normally (perpendicularly) on a surface.
    Difference:
  • Thrust is the total normal force acting on a surface.
  • Pressure is the thrust per unit area.
     Thrust is a vector quantity, while pressure is a scalar quantity.

 

  1. Define pressure and write its SI unit.
    Ans: Pressure is the thrust acting per unit area of a surface.
    Formula: Pressure = Thrust / Area
     The SI unit of pressure is pascal (Pa), where 1 pascal = 1 newton / 1 m².

 

  1. Explain how pressure depends on area. Give examples.
    Ans: Pressure is inversely proportional to the area on which the thrust acts.
  • If the area is small, pressure increases.
  • If the area is large, pressure decreases.
     Examples:
     (i) A sharp knife cuts better because it exerts high pressure on a small area.
     (ii) Broad tyres in tractors reduce pressure on the ground and prevent sinking in mud.

 

  1. State the relation between pressure, thrust, and area.
    Ans: Pressure = Thrust / Area
    This relation shows that pressure is directly proportional to thrust and inversely proportional to area. Thus, for the same thrust, a smaller area results in higher pressure, and a larger area results in lower pressure.

 

  1. What is the moment of a force? On what factors does it depend?
    Ans: Moment of a force is the turning effect of a force about a fixed point or axis.
    Formula: Moment = Force × Perpendicular distance from the pivot.
     Factors affecting moment of force:
     (i) Magnitude of the force
     (ii) Perpendicular distance from the pivot

 

  1. Explain how a spanner works based on the turning effect of force.
    Ans: A spanner is a tool used to turn bolts and nuts. It works on the principle of the moment of force. When force is applied at the end of the spanner, it turns the nut due to the turning effect. The greater the perpendicular distance from the pivot (nut), the greater the moment and hence easier the turning.

 

  1. Why is the handle of a door placed far from the hinge?
    Ans: The handle is placed far from the hinge to increase the perpendicular distance from the pivot. This increases the moment of force, making it easier to open or close the door with less effort.

 

  1. Define 1 newton.
    Ans: 1 newton is the force which, when applied on a body of mass 1 kg, produces an acceleration of 1 m/s².
    1 N = 1 kg × 1 m/s²

 

  1. What is the SI unit of moment of force? Define it.
    Ans: The SI unit of moment of force is newton-metre (N·m).
    It is defined as the moment produced by a force of 1 newton acting at a perpendicular distance of 1 metre from the pivot.

 

  1. Explain how pressure works in liquids.
    Ans: Liquids exert pressure on the walls and base of their container. The pressure in a liquid increases with the depth from the surface and depends on the density of the liquid. It acts equally in all directions at the same depth and is independent of the shape of the container.

 

  1. State two factors on which liquid pressure depends.
    Ans:
    (i) Height (or depth) of the liquid column – pressure increases with depth.
     (ii) Density of the liquid – denser liquids exert more pressure.

 

  1. Why does water come out more forcefully from the lower holes of a water tank?
    Ans: Water comes out more forcefully from the lower holes because the pressure at greater depth is higher due to the increased height of the water column.

 

  1. What is atmospheric pressure? State its value at sea level.
    Ans: Atmospheric pressure is the pressure exerted by the weight of the air above the surface of the Earth.
    Standard atmospheric pressure at sea level = 76 cm of mercury or 1.013 × 10⁵ pascal.

 

  1. How does a barometer work?
    Ans: A barometer consists of an inverted mercury-filled glass tube placed in a mercury reservoir. Atmospheric pressure pushes the mercury up the tube. The height of the mercury column gives the atmospheric pressure, usually 76 cm at sea level.

 

  1. Why is mercury used in a barometer instead of water?
    Ans: Mercury is used because it is denser than water. If water were used, the height of the column would be about 10.3 metres, making the instrument very large and inconvenient.

 

  1. Give an example from daily life where atmospheric pressure is observed.
    Ans: Drinking through a straw demonstrates atmospheric pressure. When air is sucked out of the straw, atmospheric pressure pushes the liquid up into the straw.

 

  1. Why does atmospheric pressure decrease with altitude?
    Ans: Atmospheric pressure decreases with altitude because the density and weight of the air above decrease as we move higher up from the Earth’s surface.

 

  1. How does pressure affect the design of dams?
    Ans: Dams are made thicker at the bottom because water pressure increases with depth. The thicker wall at the base can withstand the greater pressure of the water.

 

  1. What is the pressure at a point in a liquid dependent upon?
    Ans: Pressure at a point in a liquid depends on the depth of the point below the liquid surface and the density of the liquid.

 

  1. What happens to pressure when area is increased keeping thrust constant?
    Ans: Pressure decreases when the area increases for a constant thrust because pressure is inversely proportional to the area. This is why wide bases are used in foundations to reduce pressure on the ground.

 

  1. What is meant by 1 pascal pressure?
    Ans: 1 pascal pressure means a thrust of 1 newton acting on an area of 1 square metre.
    1 Pa = 1 N/m²

 

  1. Explain why a pin has a sharp point.
    Ans: A pin has a sharp point to concentrate the applied force over a very small area, thereby producing high pressure which allows it to pierce through surfaces easily.

 

  1. What is the effect of atmospheric pressure on a suction cup?
    Ans: When a suction cup is pressed against a surface, air is expelled from inside it. The atmospheric pressure acting on the outer surface then holds the cup firmly against the wall.

 

  1. Describe an activity to show that air exerts pressure.
    Ans: Take a glass filled with water and cover it with a card. Hold the card and invert the glass. The card doesn’t fall, showing that air pressure below the card supports the weight of water.

 

  1. What is the reason behind bursting of a balloon when over-inflated?
    Ans: When a balloon is over-inflated, the pressure of the air inside exceeds the atmospheric pressure and the elastic limit of the balloon, causing it to burst.

 

  1. Define pressure in liquids and explain how it is measured.
    Ans: Pressure in liquids is the force exerted by the liquid per unit area on the walls and base of the container. It is measured using devices such as U-tube manometers or pressure sensors.

 

  1. Give one example of pressure being useful in machines.
    Ans: In hydraulic lifts, pressure applied on a small piston is transmitted through the liquid to a larger piston, lifting heavy loads with relatively small force, based on Pascal’s law.

 

  1. Why do we feel pain if someone steps on us with high heels?
    Ans: High heels concentrate the body’s weight on a very small area, creating high pressure, which causes pain or injury to the surface being stepped on.

 

  1. How does a straw work using atmospheric pressure?
    Ans: When we suck air out of a straw, the pressure inside the straw decreases. The atmospheric pressure on the liquid in the container pushes the liquid up into the straw.

 

  1. Explain why we can’t live on very high mountains without oxygen cylinders.
    Ans: At very high altitudes, atmospheric pressure is very low, which reduces the amount of oxygen available for breathing. Hence, oxygen cylinders are needed to supply adequate oxygen.

 

  1. Describe the working principle of a hydraulic press.
    Ans: A hydraulic press works on Pascal’s law, which states that pressure applied at one point in a liquid is transmitted equally in all directions. This allows a small force on a small piston to lift heavy loads using a larger piston.

 

  1. Write a short note on the relationship between force, pressure, and area.
    Ans: Pressure is directly proportional to the applied force and inversely proportional to the area over which the force acts. This means that the same force exerts more pressure on a smaller area and less pressure on a larger area.

 

  1. What do you mean by equilibrium in the context of forces?
    Ans: Equilibrium occurs when all the forces acting on a body cancel out each other, resulting in no change in the state of rest or motion of the body.

 

  1. Explain why nails have pointed ends.
    Ans: Nails have pointed ends so that when a hammer strikes the nail, the force is concentrated on a small area, resulting in high pressure that allows the nail to enter the surface easily.

 

  1. Why does a wide base in buildings provide stability?
    Ans: A wide base spreads the weight of the building over a larger area, reducing the pressure on the ground and increasing stability.

 

  1. How does pressure change with depth in a fluid?
    Ans: Pressure increases with depth in a fluid because the weight of the fluid above exerts a greater force on the fluid below, leading to increased pressure.

 

  1. Define atmospheric pressure and give its SI value.
    Ans: Atmospheric pressure is the pressure exerted by the atmosphere on all bodies due to the weight of air. Its SI value is 1.013 × 10⁵ Pa at sea level.

 

  1. What are the effects of force on a body?
    Ans: Force can change the shape, size, direction, or speed of a body or cause a stationary body to start moving.

 

  1. Explain why dams are curved inwards.
    Ans: Dams are curved inwards to distribute the pressure of water more evenly and to prevent the dam from collapsing under the high pressure at greater depths.

 

  1. Why are tyres of heavy trucks wide?
    Ans: Wide tyres distribute the weight over a larger area, reducing the pressure on the road and preventing damage to road surfaces.

 

  1. What is the pressure exerted by a thrust of 200 N on an area of 2 m²?
    Ans:
    Pressure = Thrust / Area = 200 N / 2 m² = 100 Pa

 

  1. How is the pressure in fluids transmitted?
    Ans: In fluids, pressure is transmitted equally in all directions and to all parts of the fluid, which is the principle behind hydraulic devices.

 

  1. Why is a small child more likely to sink in soft mud than an adult lying flat?
    Ans: A child standing has a small area of contact with the mud, exerting more pressure, while an adult lying flat has a larger area of contact, exerting less pressure and reducing the chance of sinking.

 

  1. State and explain Pascal’s Law.
    Ans: Pascal’s Law states that pressure applied at any point in a confined fluid is transmitted equally and undiminished in all directions throughout the fluid.

 

  1. What causes pressure in gases?
    Ans: Pressure in gases is caused by the continuous and random collisions of gas molecules with the walls of the container.

 

  1. Why does a balloon expand when air is blown into it?
    Ans: The air inside creates internal pressure which exceeds the atmospheric pressure outside, causing the balloon to expand.

 

  1. How is the concept of pressure used in snowshoes?
    Ans: Snowshoes increase the area of contact with snow, reducing pressure and preventing the person from sinking into the snow.

 

  1. A force of 10 N is applied at a distance of 0.5 m from a pivot. Calculate the moment.
    Ans:
    Moment = Force × Distance = 10 N × 0.5 m = 5 N·m

 

  1. Describe how a barometer shows changes in atmospheric pressure.
    Ans: When atmospheric pressure increases, it pushes the mercury higher in the barometer tube. When it decreases, the mercury level falls, indicating changes in weather conditions.

Give Reasons

  1. Give reason: A sharp knife cuts better than a blunt one.
     Ans: A sharp knife has a smaller area of contact, so it exerts more pressure for the same force, making cutting easier.


  2. Give reason: A camel can walk easily on sand.
     Ans: A camel has broad feet which increases the area of contact, thus reducing pressure on the sand and preventing sinking.


  3. Give reason: A man exerts more pressure when standing than when lying down.
     Ans: While standing, the contact area with the ground is smaller, hence pressure increases.


  4. Give reason: The base of a dam is made thicker than the top.
     Ans: Pressure increases with depth in liquids, so the base experiences more pressure and needs to be stronger.


  5. Give reason: Water comes out faster from the lower holes of a tank.
     Ans: Pressure in a liquid increases with depth, so the lower hole has more pressure and water flows faster.


  6. Give reason: Nails have pointed ends.
     Ans: The pointed end has a very small area, so it exerts a large pressure, allowing it to penetrate surfaces easily.


  7. Give reason: Buildings have wide foundations.
     Ans: A wide foundation spreads the weight over a large area, reducing pressure on the ground.


  8. Give reason: Balloons burst when over-inflated.
     Ans: The internal air pressure becomes greater than the elastic limit of the balloon, causing it to burst.


  9. Give reason: It is difficult to walk on sand with high heels.
     Ans: High heels have a small area of contact, which increases pressure and causes the heels to sink into the sand.


  10. Give reason: The handle of a door is fixed far from the hinge.
     Ans: To increase the perpendicular distance from the pivot, thereby increasing the moment of force and making it easier to open.


  11. Give reason: We feel pain when someone steps on us with a pointed heel.
     Ans: The small area increases the pressure exerted, which can be painful.


  12. Give reason: We are able to drink using a straw.
     Ans: Sucking air from the straw reduces pressure inside, and atmospheric pressure pushes the liquid up.


  13. Give reason: A barometer uses mercury instead of water.
     Ans: Mercury is much denser than water, so a shorter column is sufficient to measure atmospheric pressure.


  14. Give reason: The pressure in a liquid increases with depth.
     Ans: The deeper a point is in a liquid, the more weight of the liquid acts above it, increasing pressure.


  15. Give reason: Atmospheric pressure decreases with height.
     Ans: As altitude increases, the density and weight of air above decrease, leading to lower pressure.


  16. Give reason: A suction cup sticks to a smooth surface.
     Ans: Air is expelled from inside the cup, and atmospheric pressure outside presses it against the surface.


  17. Give reason: Water exerts pressure in all directions.
     Ans: Liquid molecules apply force in all directions due to their random motion.


  18. Give reason: A spanner is an efficient tool to rotate bolts.
     Ans: It applies force at a distance from the pivot, creating a greater moment and making rotation easier.


  19. Give reason: The mercury level in a barometer falls on a mountain.
     Ans: Atmospheric pressure is lower at higher altitudes, so the mercury column height decreases.


  20. Give reason: Tyres of heavy trucks are wide.
     Ans: Wide tyres distribute weight over a larger area, reducing pressure on roads.


  21. Give reason: Pressure is more when area is less.
     Ans: Pressure is inversely proportional to area; hence less area means more pressure for the same force.


  22. Give reason: Pressure is measured in pascal.
     Ans: One pascal is defined as a thrust of one newton acting on an area of one square metre.


  23. Give reason: Mercury is suitable for barometers.
     Ans: It has high density, low vapour pressure, and doesn’t stick to glass.


  24. Give reason: A wedge is used to split wood.
     Ans: A wedge has a sharp edge with small area, producing high pressure for splitting.


  25. Give reason: Pressure in fluids is transmitted equally in all directions.
     Ans: Fluids do not have a fixed shape, so pressure distributes uniformly in all directions at a given depth.


  26. Give reason: A small child may sink in soft mud but not an adult lying flat.
     Ans: The child has smaller area of contact, exerting higher pressure, while the adult lying flat exerts less pressure.


  27. Give reason: When force increases, pressure increases.
     Ans: Pressure is directly proportional to force when area is constant.


  28. Give reason: A rubber sucker sticks to a surface but falls in vacuum.
     Ans: Atmospheric pressure holds it in place, but in vacuum, there is no pressure to press it against the surface.


  29. Give reason: Barometer is used to forecast weather.
     Ans: Atmospheric pressure changes indicate upcoming weather conditions like rain or storms.


  30. Give reason: Water rises in a syringe when the plunger is pulled.
     Ans: The pressure inside decreases, and atmospheric pressure pushes the water into the syringe.


  31. Give reason: Lying flat reduces pressure on a surface.
     Ans: The area of contact increases, thus reducing the pressure.


  32. Give reason: A wheelbarrow is easier to lift from the handles.
     Ans: The handles are farther from the pivot, increasing the moment of force.


  33. Give reason: Deep-sea creatures have strong bodies.
     Ans: They need to withstand the extremely high pressure due to the depth of water above them.


  34. Give reason: Hydraulics use liquids and not gases.
     Ans: Liquids are incompressible, so pressure is transmitted uniformly without loss.


  35. Give reason: A person is advised not to climb mountains rapidly.
     Ans: At high altitudes, low atmospheric pressure can cause breathing problems due to less oxygen availability.


  36. Give reason: Foundations of dams are built very strong.
     Ans: They have to resist the high water pressure at the bottom.


  37. Give reason: Atmospheric pressure supports the mercury column in a barometer.
     Ans: The pressure from the air balances the weight of the mercury column.


  38. Give reason: Pressure in gases is due to collision of molecules.
     Ans: Gas molecules move randomly and collide with the container walls, creating pressure.


  39. Give reason: We cannot blow a balloon infinitely.
     Ans: Beyond a certain limit, the internal pressure exceeds the elastic capacity of the balloon, causing it to burst.


  40. Give reason: A blunt knife doesn’t cut well.
     Ans: It has a larger contact area and hence exerts less pressure.


  41. Give reason: A crowbar is a good example of force multiplier.
     Ans: It allows a small effort to create a large output force using the turning effect.


  42. Give reason: Snowshoes help in walking on snow.
     Ans: They increase the surface area, reducing pressure on the snow.


  43. Give reason: A barometer cannot be used to measure liquid pressure.
     Ans: A barometer measures atmospheric pressure, not the pressure inside liquids.


  44. Give reason: Atmospheric pressure can crush objects.
     Ans: It acts in all directions and can collapse hollow objects if internal pressure is low.


  45. Give reason: The thrust acting on a given area can vary.
     Ans: Thrust depends on the magnitude of the applied force and its direction.


  46. Give reason: A U-tube manometer can measure pressure difference.
     Ans: The height difference of liquid columns indicates the difference in pressure between two points.


  47. Give reason: Large water tanks are placed at heights.
     Ans: To provide sufficient water pressure due to the height of the water column.


  48. Give reason: Liquids are stored in strong containers.
     Ans: To withstand the pressure exerted by the liquid, especially at the base.


  49. Give reason: Pressure has no direction.
     Ans: Pressure is a scalar quantity; it only has magnitude, not direction.


  50. Give reason: The tip of a needle is pointed.
     Ans: To apply force over a very small area, thereby increasing pressure for easy penetration.

Arrange the Words 

Case Studies

Case Study 1:
 Rita observed that when she used a sharp knife, she could cut vegetables with ease. But when the knife became blunt, it was harder to use.
 Q1. Why is a sharp knife more effective?
 Ans: It has a smaller area of contact, thus exerts greater pressure.
 Q2. What happens to pressure when area increases?
 Ans: Pressure decreases.

 

Case Study 2:
 A dam is being constructed on a river. The engineers designed the base of the dam thicker than the top.
 Q1. Why is the base of the dam made thicker?
 Ans: Because water pressure increases with depth.
 Q2. Which factor affects liquid pressure here?
 Ans: Height of the liquid column.

 

Case Study 3:
 Rahul noticed that water comes out faster from the lower hole of a bottle than the upper one.
 Q1. What is the reason for this observation?
 Ans: Liquid pressure increases with depth.
 Q2. What type of pressure is responsible here?
 Ans: Liquid pressure.

 

Case Study 4:
 Meena stepped on wet sand wearing high heels and sank into it. Her friend wore flat slippers and did not sink.
 Q1. Why did Meena sink into the sand?
 Ans: The small area of heels exerted more pressure.
 Q2. Which formula explains this situation?
 Ans: Pressure = Force / Area.

 

Case Study 5:
 At a science exhibition, students demonstrated how a straw helps in drinking juice.
 Q1. What causes juice to rise in the straw?
 Ans: Atmospheric pressure.
 Q2. What happens to the pressure inside the straw when air is sucked out?
 Ans: It decreases.

 

Case Study 6:
 A balloon bursts when too much air is blown into it.
 Q1. Why does the balloon burst?
 Ans: Air pressure inside exceeds the elastic limit of the balloon.
 Q2. What kind of pressure is involved?
 Ans: Air (gas) pressure.

 

Case Study 7:
 A mechanic uses a spanner to loosen a tight bolt. He applies the force at the farthest end of the spanner.
 Q1. Why does he apply force at the far end?
 Ans: To increase the turning effect (moment of force).
 Q2. Name the quantity: Force × Perpendicular distance.
 Ans: Moment of force.

 

Case Study 8:
 A suction cup sticks firmly to a glass window when pressed.
 Q1. What causes the cup to stick?
 Ans: Atmospheric pressure outside the cup holds it.
 Q2. What happens inside the cup when pressed?
 Ans: Air is removed, creating low pressure.

 

Case Study 9:
 A water tank is mounted on the terrace to supply water to the building below.
 Q1. Why is the tank placed at a height?
 Ans: To provide enough water pressure due to gravity.
 Q2. Which factor affects pressure here?
 Ans: Height of the water column.

 

Case Study 10:
 In a lab experiment, a barometer showed a mercury column height of 76 cm.
 Q1. What does this reading represent?
 Ans: Standard atmospheric pressure.
 Q2. Why is mercury used?
 Ans: Because of its high density and low vapour pressure.

 

Case Study 11:
 Ajay noticed that nails enter wood easily when struck with a hammer.
 Q1. Why do nails enter wood more easily?
 Ans: The sharp tip exerts high pressure on the surface.
 Q2. What is the effect of reducing area on pressure?
 Ans: It increases pressure.

 

Case Study 12:
 A hydraulic lift raises a car with a small applied force.
 Q1. What law is the lift based on?
 Ans: Pascal’s law.
 Q2. What property of liquid enables this?
 Ans: Pressure is transmitted equally in all directions in a liquid.

 

Case Study 13:
 A climber uses wide snow shoes to avoid sinking into the snow.
 Q1. Why do wide shoes help?
 Ans: They increase area and reduce pressure.
 Q2. Which formula supports this reasoning?
 Ans: Pressure = Force / Area.

 

Case Study 14:
 A barometer reads 72 cm in a city.
 Q1. Is atmospheric pressure more or less than normal?
 Ans: Less than standard atmospheric pressure.
 Q2. What weather might this indicate?
 Ans: Possibility of rain or a storm.

 

Case Study 15:
 A girl pushes open a door by applying force at its handle, far from the hinge.
 Q1. Why is the handle placed far from the hinge?
 Ans: To increase the moment of force.
 Q2. Which two factors affect moment?
 Ans: Force and perpendicular distance from pivot.

 

Case Study 16:
 Sohan tried to lift a brick by hand but failed. He used a lever and succeeded.
 Q1. What did the lever help him increase?
 Ans: Moment of force.
 Q2. What does the pivot represent in this setup?
 Ans: The fixed point about which the lever rotates.

 

Case Study 17:
 A deep-sea diver experiences more pressure underwater.
 Q1. Why does pressure increase with depth?
 Ans: Due to the weight of the liquid above.
 Q2. Name one factor affecting liquid pressure.
 Ans: Depth (or height of liquid column).

 

Case Study 18:
 A balloon shrinks when taken to a high-altitude area.
 Q1. Why does the balloon shrink?
 Ans: Atmospheric pressure decreases, so internal pressure compresses it.
 Q2. How does atmospheric pressure change with height?
 Ans: It decreases with increase in height.

 

Case Study 19:
 In a hydraulic braking system, a small force on the pedal stops the vehicle.
 Q1. Which principle is used in this system?
 Ans: Pascal’s law.
 Q2. Why are liquids used instead of gases?
 Ans: Liquids are incompressible and transmit pressure efficiently.

 

Case Study 20:
 Kiran’s teacher showed that pressing a rubber ball changes its shape.
 Q1. Which effect of force is demonstrated?
 Ans: Force changes the shape of a body.
 Q2. Name two other effects of force.
 Ans: It can start motion or change the direction/speed of motion.

Numericals

  1. A force of 50 N is applied over an area of 2 m². Calculate the pressure.
    Ans: Pressure = Force / Area = 50 / 2 = 25 Pa

 

  1. A thrust of 120 N acts on an area of 0.4 m². Find the pressure.
    Ans: Pressure = 120 / 0.4 = 300 Pa

 

  1. A pressure of 200 Pa acts on a surface area of 5 m². Calculate the thrust.
    Ans: Thrust = Pressure × Area = 200 × 5 = 1000 N

 

  1. A boy applies a force of 30 N on a box. If the box does not move, what is the pressure applied if the area is 0.5 m²?
    Ans: Pressure = 30 / 0.5 = 60 Pa

 

  1. A force of 10 N is applied perpendicular to a surface area of 0.2 m². Find the pressure.
    Ans: Pressure = 10 / 0.2 = 50 Pa

 

  1. A thrust of 800 N acts on a surface of area 4 m². Find the pressure.
    Ans: Pressure = 800 / 4 = 200 Pa

 

  1. A body of mass 5 kg is placed on a table of area 0.25 m². Calculate the pressure. (Take g = 10 m/s²)
    Ans: Force = m × g = 5 × 10 = 50 N
    Pressure = 50 / 0.25 = 200 Pa

 

  1. A man weighing 600 N stands on a wooden plank of area 1.5 m². Find the pressure exerted.
    Ans: Pressure = 600 / 1.5 = 400 Pa

 

  1. A brick weighing 200 N is placed on the ground with its base area 0.05 m². Calculate the pressure.
    Ans: Pressure = 200 / 0.05 = 4000 Pa

 

  1. A liquid exerts a pressure of 5000 Pa at a depth of 5 m. Calculate the density. (Take g = 10 m/s²)
    Ans: Pressure = hρg → ρ = P / (h × g) = 5000 / (5 × 10) = 100 kg/m³

 

  1. Calculate the moment of force if a force of 15 N is applied at a perpendicular distance of 0.6 m from the pivot.
    Ans: Moment = Force × Distance = 15 × 0.6 = 9 N·m

 

  1. A wrench is 0.3 m long. A force of 50 N is applied at its end. Calculate the moment of force.
    Ans: Moment = 50 × 0.3 = 15 N·m

 

  1. If pressure is 1000 Pa and area is 2.5 m², calculate the thrust.
    Ans: Thrust = Pressure × Area = 1000 × 2.5 = 2500 N

 

  1. A pressure of 400 Pa acts on a surface of area 0.8 m². What is the thrust?
    Ans: Thrust = 400 × 0.8 = 320 N

 

  1. A boy exerts a thrust of 180 N over an area of 0.3 m². Find the pressure.
    Ans: Pressure = 180 / 0.3 = 600 Pa

 

  1. A body exerts a pressure of 250 Pa over an area of 1.6 m². Find the thrust.
    Ans: Thrust = 250 × 1.6 = 400 N

 

  1. A student applies a force of 10 N on a door at a distance of 0.75 m from the hinge. Calculate the moment.
    Ans: Moment = 10 × 0.75 = 7.5 N·m

 

  1. Calculate the moment of force when a force of 8 N is applied at a perpendicular distance of 2 m.
    Ans: Moment = 8 × 2 = 16 N·m

 

  1. A machine applies a pressure of 10000 Pa over an area of 0.02 m². Find the thrust.
    Ans: Thrust = 10000 × 0.02 = 200 N

 

  1. A girl weighing 500 N stands on one foot of area 0.025 m². Calculate the pressure.
    Ans: Pressure = 500 / 0.025 = 20000 Pa

 

  1. If a thrust of 300 N is applied on an area of 1.5 m², what is the pressure?
    Ans: Pressure = 300 / 1.5 = 200 Pa

 

  1. A brick is placed on the floor with a face area of 0.01 m² and exerts 100 N force. Calculate pressure.
    Ans: Pressure = 100 / 0.01 = 10000 Pa

 

  1. A boy weighing 400 N lies on a bed of area 2 m². What is the pressure?
    Ans: Pressure = 400 / 2 = 200 Pa

 

  1. Calculate the force required to produce a pressure of 500 Pa over an area of 0.4 m².
    Ans: Force = 500 × 0.4 = 200 N

 

  1. A car exerts a total thrust of 20000 N on the road. If its contact area is 4 m², calculate the pressure.
    Ans: Pressure = 20000 / 4 = 5000 Pa

 

  1. A school bag exerts a thrust of 120 N on a student’s shoulder with a strap area of 0.01 m². Calculate pressure.
    Ans: Pressure = 120 / 0.01 = 12000 Pa

 

  1. A thrust of 360 N acts on a surface area of 0.6 m². Calculate the pressure.
    Ans: Pressure = 360 / 0.6 = 600 Pa

 

  1. Calculate the thrust produced when pressure is 1500 Pa and area is 3 m².
    Ans: Thrust = 1500 × 3 = 4500 N

 

  1. A bottle exerts 50 N force on a table. If its base area is 0.025 m², find the pressure.
    Ans: Pressure = 50 / 0.025 = 2000 Pa

 

  1. A force of 25 N is applied at a distance of 0.2 m. Find the moment.
    Ans: Moment = 25 × 0.2 = 5 N·m

 

  1. An area of 0.04 m² experiences a pressure of 10000 Pa. Find the thrust.
    Ans: Thrust = 10000 × 0.04 = 400 N

 

  1. A sharp knife of area 0.0005 m² is pressed with 100 N force. Find pressure.
    Ans: Pressure = 100 / 0.0005 = 200000 Pa

 

  1. A brick of mass 10 kg is placed on a surface of area 0.02 m². Find pressure. (g = 10 m/s²)
    Ans: Force = 10 × 10 = 100 N
    Pressure = 100 / 0.02 = 5000 Pa

 

  1. A boy applies 70 N force at a distance of 0.9 m from pivot. Find the moment.
    Ans: Moment = 70 × 0.9 = 63 N·m

 

  1. A cylinder applies 200 N force on a table. Base area = 0.1 m². Find pressure.
    Ans: Pressure = 200 / 0.1 = 2000 Pa

 

  1. Calculate pressure when thrust = 400 N and area = 0.5 m².
    Ans: Pressure = 400 / 0.5 = 800 Pa

 

  1. If a woman of weight 500 N stands on two feet of total area 0.05 m², calculate pressure.
    Ans: Pressure = 500 / 0.05 = 10000 Pa

 

  1. A barometer shows height of 76 cm of mercury. Convert to mm.
    Ans: 76 cm = 760 mm

 

  1. A moment of 12 N·m is produced by a 6 N force. What is the perpendicular distance?
    Ans: Distance = Moment / Force = 12 / 6 = 2 m

 

  1. A girl applies 90 N force using a crowbar at 1.2 m from pivot. Find moment.
    Ans: Moment = 90 × 1.2 = 108 N·m

 

  1. A 600 N man stands on a plank of area 0.3 m². Find pressure.
    Ans: Pressure = 600 / 0.3 = 2000 Pa

 

  1. A thrust of 100 N is distributed over 0.25 m². Find pressure.
    Ans: Pressure = 100 / 0.25 = 400 Pa

 

  1. A carpenter applies 60 N force at 0.5 m from the hinge of a door. Find the moment.
    Ans: Moment = 60 × 0.5 = 30 N·m

 

  1. Calculate the force when pressure = 2500 Pa and area = 2 m².
    Ans: Force = 2500 × 2 = 5000 N

 

  1. A man exerts a pressure of 12000 Pa while standing. His area of contact = 0.04 m². Find thrust.
    Ans: Thrust = 12000 × 0.04 = 480 N

 

  1. A wedge presses into wood with 300 N force over area 0.005 m². Calculate pressure.
    Ans: Pressure = 300 / 0.005 = 60000 Pa

 

  1. A football is kicked with 20 N at 0.25 m from pivot. Find moment.
    Ans: Moment = 20 × 0.25 = 5 N·m

 

  1. If pressure is 350 Pa and thrust is 175 N, what is the area?
    Ans: Area = Thrust / Pressure = 175 / 350 = 0.5 m²

 

  1. A weight of 980 N rests on a platform of area 0.7 m². Find pressure.
    Ans: Pressure = 980 / 0.7 = 1400 Pa

 

  1. A hydraulic lift exerts 15000 N thrust over 3 m². Find pressure.
    Ans: Pressure = 15000 / 3 = 5000 Pa

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