ICSE – Grade 10 – Physics – Ch 02 – QA

Questions & Answers

ICSE - Grade - 10

Subject: Physics

Chapter - 02 - Work, Energy and Power

Types of Questions

MCQ

  1. Work is said to be done only when:
    A) Force is applied
    B) Object moves
     C) Force causes displacement
     D) Both A and C
     Answer: D) Both A and C

 

  1. SI unit of work is:
    A) Erg
    B) Joule
     C) Watt
     D) Calorie
     Answer: B) Joule

 

  1. Work done when force is perpendicular to displacement is:
    A) Maximum
    B) Minimum
     C) Positive
     D) Zero
     Answer: D) Zero

 

  1. Which formula is correct for work done?
    A) W = F + S
    B) W = F × S × cosθ
     C) W = F/S
     D) W = S × θ
     Answer: B) W = F × S × cosθ

 

  1. If an object is displaced opposite to the force, the work done is:
    A) Zero
    B) Positive
     C) Negative
     D) Infinite
     Answer: C) Negative

 

  1. Work is a:
    A) Vector
    B) Tensor
     C) Scalar
     D) Matrix
     Answer: C) Scalar

 

  1. The relation between joule and erg is:
    A) 1 J = 10⁵ erg
    B) 1 J = 10⁶ erg
     C) 1 J = 10⁷ erg
     D) 1 J = 10⁸ erg
     Answer: C) 1 J = 10⁷ erg

 

  1. Power is defined as:
    A) Force per unit time
    B) Work per unit distance
     C) Work per unit time
     D) Energy per unit mass
     Answer: C) Work per unit time

 

  1. 1 kilowatt =
    A) 100 W
    B) 10⁵ W
     C) 1000 W
     D) 10⁶ W
     Answer: C) 1000 W

 

  1. Horsepower is a unit of:
    A) Energy
    B) Force
     C) Work
     D) Power
     Answer: D) Power

 

  1. 1 horsepower =
    A) 1000 W
    B) 746 W
     C) 1.5 kW
     D) 3600 W
     Answer: B) 746 W

 

  1. Energy is defined as:
    A) Force × mass
    B) Rate of work
     C) Capacity to do work
     D) Displacement × acceleration
     Answer: C) Capacity to do work

 

  1. The SI unit of energy is:
    A) Erg
    B) Watt
     C) Joule
     D) Calorie
     Answer: C) Joule

 

  1. Work-energy theorem states:
    A) Work done = Force × distance
    B) Work done = change in potential energy
     C) Work done = change in kinetic energy
     D) Work done = force × time
     Answer: C) Work done = change in kinetic energy

 

  1. Kinetic energy of a body is given by:
    A) mv²
    B) ½mv²
     C) mgh
     D) F × t
     Answer: B) ½mv²

 

  1. The potential energy of a body at height h is:
    A) mgh
    B) ½mv²
     C) F × S
     D) mv
     Answer: A) mgh

 

  1. If a moving object is brought to rest, its kinetic energy becomes:
    A) Zero
    B) Maximum
     C) Infinite
     D) Constant
     Answer: A) Zero

 

  1. When an object falls freely, its total mechanical energy:
    A) Increases
    B) Decreases
     C) Remains constant
     D) Becomes zero
     Answer: C) Remains constant

 

  1. 1 kilowatt-hour =
    A) 1000 J
    B) 3600 J
     C) 3.6 × 10⁶ J
     D) 3.6 × 10⁴ J
     Answer: C) 3.6 × 10⁶ J

 

  1. Which of the following is not a form of mechanical energy?
    A) Potential energy
    B) Kinetic energy
     C) Nuclear energy
     D) Both A and B
     Answer: C) Nuclear energy

 

  1. Work done when an object moves with constant velocity under balanced forces is:
    A) Positive
    B) Negative
     C) Zero
     D) Infinite
     Answer: C) Zero

 

  1. The energy possessed due to motion is:
    A) Kinetic energy
    B) Potential energy
     C) Heat energy
     D) Chemical energy
     Answer: A) Kinetic energy

 

  1. 1 eV =
    A) 1.6 × 10⁻¹⁹ J
    B) 1.6 × 10⁻¹⁶ J
     C) 1.6 × 10⁻¹² J
     D) 1.6 × 10⁻⁹ J
     Answer: A) 1.6 × 10⁻¹⁹ J

 

  1. Heat energy is measured in:
    A) Newton
    B) Joule
     C) Calorie
     D) Watt
     Answer: C) Calorie

 

  1. The force-displacement graph gives work as:
    A) Slope
    B) Area under the curve
     C) Tangent
     D) None
     Answer: B) Area under the curve

 

  1. If θ = 0°, work done is:
    A) Zero
    B) Negative
     C) Positive
     D) Undefined
     Answer: C) Positive

 

  1. Vibrational kinetic energy is associated with:
    A) Free fall
    B) Rotation
     C) To and fro motion
     D) Circular motion
     Answer: C) To and fro motion

 

  1. Rotational kinetic energy is possessed by:
    A) A car moving in a line
    B) A spinning top
     C) A falling ball
     D) A stretched spring
     Answer: B) A spinning top

 

  1. Gravitational potential energy depends on:
    A) Speed
    B) Height
     C) Volume
     D) Density
     Answer: B) Height

 

  1. The kinetic energy of a body becomes four times if its speed becomes:
    A) 2 times
    B) 4 times
     C) 8 times
     D) 16 times
     Answer: A) 2 times

 

  1. Which of these is a scalar quantity?
    A) Force
    B) Displacement
     C) Work
     D) Velocity
     Answer: C) Work

 

  1. Which physical quantity has unit J/s?
    A) Work
    B) Power
     C) Energy
     D) Force
     Answer: B) Power

 

  1. Mechanical energy includes:
    A) Electrical and heat energy
    B) Kinetic and potential energy
     C) Light and chemical energy
     D) Sound and heat energy
     Answer: B) Kinetic and potential energy

 

  1. If a body is moving in a circle with constant speed, the work done is:
    A) Zero
    B) Positive
     C) Negative
     D) Maximum
     Answer: A) Zero

 

  1. Unit of work in CGS system is:
    A) Dyne
    B) Erg
     C) Calorie
     D) Newton
     Answer: B) Erg

 

  1. Work done in lifting a body of mass m to height h:
    A) Zero
    B) m × g × h
     C) m × v²
     D) m × a × t
     Answer: B) m × g × h

 

  1. What happens to kinetic energy if mass is doubled and velocity remains same?
    A) Halved
    B) Doubled
     C) Tripled
     D) Same
     Answer: B) Doubled

 

  1. Rate of doing work is called:
    A) Energy
    B) Power
     C) Displacement
     D) Force
     Answer: B) Power

 

  1. A stretched spring has:
    A) Gravitational P.E.
    B) Kinetic energy
     C) Elastic potential energy
     D) No energy
     Answer: C) Elastic potential energy

 

  1. A freely falling body converts its:
    A) K.E. to P.E.
    B) P.E. to K.E.
     C) Mass to energy
     D) Energy to force
     Answer: B) P.E. to K.E.

 

  1. Work done by gravity is:
    A) Always zero
    B) Always negative
     C) Positive when falling
     D) Positive only when at rest
     Answer: C) Positive when falling

 

  1. A ball rolling on a horizontal surface has:
    A) P.E. only
    B) K.E. only
     C) No energy
     D) Both P.E. and K.E.
     Answer: B) K.E. only

 

  1. What happens to P.E. at ground level?
    A) Becomes zero
    B) Becomes maximum
     C) Remains constant
     D) Increases
     Answer: A) Becomes zero

 

  1. Work is zero if:
    A) Force is applied
    B) Displacement occurs
     C) Force and displacement are perpendicular
     D) Object accelerates
     Answer: C) Force and displacement are perpendicular

 

  1. Mechanical energy is conserved when:
    A) Friction is present
    B) Air resistance is present
     C) No friction or resistance
     D) Object is at rest
     Answer: C) No friction or resistance

 

  1. A 60 W bulb consumes how much energy in 1 hour?
    A) 3600 J
    B) 216000 J
     C) 36000 J
     D) 60000 J
     Answer: B) 216000 J

 

  1. The graph of constant force vs displacement is:
    A) Parabola
    B) Curve
     C) Straight line
     D) Sine wave
     Answer: C) Straight line

 

  1. Example of chemical to electrical energy conversion:
    A) Electric fan
    B) Battery
     C) Solar panel
     D) Generator
     Answer: B) Battery

 

  1. 1 calorie =
    A) 4.18 J
    B) 3.6 J
     C) 2.14 J
     D) 1.6 J
     Answer: A) 4.18 J

 

  1. The total energy of a simple pendulum remains:
    A) Zero
    B) Constant
     C) Maximum at all points
     D) Minimum at mean position
     Answer: B) Constant

Fill in the Blanks

  1. Work is said to be done when a __________ causes displacement.
    Answer: force

 

  1. The SI unit of work is __________.
    Answer: joule

 

  1. Work is a __________ quantity.
    Answer: scalar

 

  1. When displacement is perpendicular to the direction of force, work done is __________.
    Answer: zero

 

  1. If displacement is in the direction opposite to the force, work is __________.
    Answer: negative

 

  1. The mathematical expression for work is W = __________.
    Answer: F × S × cosθ

 

  1. 1 joule = __________ dyne × cm
    Answer: 10⁷

 

  1. Power is defined as the __________ of doing work.
    Answer: rate

 

  1. SI unit of power is __________.
    Answer: watt

 

  1. 1 kilowatt = __________ watts
    Answer: 1000

 

  1. 1 horsepower = __________ watts
    Answer: 746

 

  1. Energy is the __________ to do work.
    Answer: capacity

 

  1. The energy possessed by a body by virtue of motion is __________ energy.
    Answer: kinetic

 

  1. The energy possessed by a body by virtue of position is __________ energy.
    Answer: potential

 

  1. Potential energy is given by the formula __________.
    Answer: mgh

 

  1. Kinetic energy is given by the formula __________.
    Answer: ½ mv²

 

  1. The unit of energy in CGS system is __________.
    Answer: erg

 

  1. 1 kilowatt-hour = __________ joules
    Answer: 3.6 × 10⁶

 

  1. The work-energy theorem states that work done = change in __________ energy.
    Answer: kinetic

 

  1. Work done is zero when force is applied but there is no __________.
    Answer: displacement

 

  1. If θ = 90°, then cosθ = __________.
    Answer: 0

 

  1. A stretched spring possesses __________ potential energy.
    Answer: elastic

 

  1. A freely falling body loses potential energy and gains __________ energy.
    Answer: kinetic

 

  1. Energy can neither be created nor destroyed. This is the law of __________ of energy.
    Answer: conservation

 

  1. The total mechanical energy of a freely falling object remains __________.
    Answer: constant

 

  1. The force-displacement graph gives work done as the __________ under the curve.
    Answer: area

 

  1. Power spent = __________ / time
    Answer: work

 

  1. Work is positive when the angle between force and displacement is __________ degrees.
    Answer: 0

 

  1. The SI unit of energy is __________.
    Answer: joule

 

  1. 1 calorie = __________ joules
    Answer: 4.18

 

  1. 1 watt = __________ joule per second
    Answer: 1

 

  1. An electric bulb converts electrical energy into __________ and light energy.
    Answer: heat

 

  1. The form of kinetic energy in a moving car is __________ kinetic energy.
    Answer: translational

 

  1. When an object is at rest at a height, it has only __________ energy.
    Answer: potential

 

  1. Mechanical energy is the sum of kinetic and __________ energy.
    Answer: potential

 

  1. The kinetic energy of a body becomes four times if its speed is __________.
    Answer: doubled

 

  1. 1 electron volt = __________ joules
    Answer: 1.6 × 10⁻¹⁹

 

  1. A fan converts electrical energy into __________ energy.
    Answer: mechanical

 

  1. Heat energy is commonly measured in __________.
    Answer: calories

 

  1. When a body moves in a circle at constant speed, work done is __________.
    Answer: zero

 

  1. Energy stored in a charged battery is __________ energy.
    Answer: chemical

 

  1. A pendulum at the mean position has maximum __________ energy.
    Answer: kinetic

 

  1. A pendulum at the extreme position has maximum __________ energy.
    Answer: potential

 

  1. In absence of friction, mechanical energy is __________.
    Answer: conserved

 

  1. A solar panel converts __________ energy to electrical energy.
    Answer: solar

 

  1. The energy due to vibration of molecules is called __________ energy.
    Answer: heat

 

  1. Energy from uranium nuclei is __________ energy.
    Answer: nuclear

 

  1. Energy due to movement of electrons is __________ energy.
    Answer: electrical

 

  1. Electrical energy to sound energy occurs in a __________.
    Answer: loudspeaker

 

  1. The unit of work is same as the unit of __________.
    Answer: energy

Name the Following

  1. Name the physical quantity defined as force × displacement × cosθ.
    Answer: Work

 

  1. Name the unit of work in SI system.
    Answer: Joule

 

  1. Name the unit of work in CGS system.
    Answer: Erg

 

  1. Name the condition when work done is zero despite the application of force.
    Answer: No displacement or displacement is perpendicular to force

 

  1. Name the physical quantity which is the rate of doing work.
    Answer: Power

 

  1. Name the SI unit of power.
    Answer: Watt

 

  1. Name the commercial unit of energy used in households.
    Answer: Kilowatt-hour (kWh)

 

  1. Name the energy possessed by a body due to its motion.
    Answer: Kinetic energy

 

  1. Name the energy possessed by a body due to its position.
    Answer: Potential energy

 

  1. Name the expression for kinetic energy.
    Answer: ½ mv²

 

  1. Name the expression for gravitational potential energy.
    Answer: mgh

 

  1. Name the energy stored in a stretched spring.
    Answer: Elastic potential energy

 

  1. Name the law that states energy can neither be created nor destroyed.
    Answer: Law of conservation of energy

 

  1. Name the energy possessed by a body at the highest point of a swing.
    Answer: Potential energy

 

  1. Name the energy possessed by a body at the mean position of a pendulum.
    Answer: Kinetic energy

 

  1. Name the device which converts mechanical energy into electrical energy.
    Answer: Generator

 

  1. Name the device which converts electrical energy into mechanical energy.
    Answer: Electric motor

 

  1. Name the unit of energy used in calorimetry.
    Answer: Calorie

 

  1. Name the smallest unit of energy used in atomic physics.
    Answer: Electron volt (eV)

 

  1. Name the relation between work and energy.
    Answer: Energy is the capacity to do work

 

  1. Name the scalar product of force and displacement.
    Answer: Work

 

  1. Name the form of energy produced by vibration.
    Answer: Sound energy

 

  1. Name the form of energy obtained from sunlight.
    Answer: Solar energy

 

  1. Name the form of energy obtained from moving water.
    Answer: Hydro energy

 

  1. Name the form of energy obtained from nuclear reactions.
    Answer: Nuclear energy

 

  1. Name the form of energy in food and fuels.
    Answer: Chemical energy

 

  1. Name the form of energy in flowing electrons.
    Answer: Electrical energy

 

  1. Name the energy conversion in a battery.
    Answer: Chemical to electrical

 

  1. Name the energy conversion in an electric bulb.
    Answer: Electrical to heat and light

 

  1. Name the energy conversion in a solar cell.
    Answer: Solar to electrical

 

  1. Name the energy conversion in a microphone.
    Answer: Sound to electrical

 

  1. Name the energy conversion in a loudspeaker.
    Answer: Electrical to sound

 

  1. Name the point where total mechanical energy of a pendulum is maximum.
    Answer: At any point (it remains constant)

 

  1. Name the term for the product of power and time.
    Answer: Work or energy

 

  1. Name the energy conversion in a thermal power plant.
    Answer: Heat to electrical

 

  1. Name the quantity whose unit is joule per second.
    Answer: Power

 

  1. Name the two components required to calculate work.
    Answer: Force and displacement

 

  1. Name the quantity that remains conserved during free fall in vacuum.
    Answer: Mechanical energy

 

  1. Name the type of energy possessed by a compressed gas.
    Answer: Potential energy

 

  1. Name the energy possessed by a hammer held above a nail.
    Answer: Gravitational potential energy

 

  1. Name the type of energy a rolling ball possesses.
    Answer: Kinetic energy

 

  1. Name the condition under which no work is said to be done.
    Answer: Displacement is zero or perpendicular to force

 

  1. Name the energy transformation in a hydroelectric plant.
    Answer: Potential to kinetic to electrical

 

  1. Name the unit of energy that equals 3.6 × 10⁶ J.
    Answer: Kilowatt-hour

 

  1. Name the energy possessed by a rotating wheel.
    Answer: Rotational kinetic energy

 

  1. Name the factor that affects both work and energy.
    Answer: Force

 

  1. Name the quantity that is the dot product of two vectors.
    Answer: Work

 

  1. Name the type of kinetic energy in a vibrating tuning fork.
    Answer: Vibrational kinetic energy

 

  1. Name the energy conversion when a person climbs stairs.
    Answer: Chemical to mechanical to potential

 

  1. Name the quantity defined as energy consumed per unit time.
    Answer: Power

Answer in One Word

  1. What is the SI unit of work?
    Answer: Joule

 

  1. What is the CGS unit of energy?
    Answer: Erg

 

  1. What quantity is the product of force and displacement in the direction of force?
    Answer: Work

 

  1. What is the rate of doing work called?
    Answer: Power

 

  1. What is the energy of motion known as?
    Answer: Kinetic

 

  1. What type of energy is stored in a stretched spring?
    Answer: Elastic

 

  1. What energy is possessed by a body due to its height above ground?
    Answer: Potential

 

  1. What is the SI unit of power?
    Answer: Watt

 

  1. What is the commercial unit of energy?
    Answer: Kilowatt-hour

 

  1. What is the energy possessed by a moving body?
    Answer: Kinetic

 

  1. What is the energy possessed by a stationary object at a height?
    Answer: Potential

 

  1. Which law states that energy cannot be created or destroyed?
    Answer: Conservation

 

  1. Which form of energy is generated by vibrating bodies?
    Answer: Sound

 

  1. What type of energy is stored in food and fuel?
    Answer: Chemical

 

  1. What type of energy is released in atomic reactions?
    Answer: Nuclear

 

  1. What energy is obtained from the sun?
    Answer: Solar

 

  1. What is the energy due to the flow of electrons called?
    Answer: Electrical

 

  1. What is equal to power multiplied by time?
    Answer: Work

 

  1. What is the alternative unit of power equal to 746 watts?
    Answer: Horsepower

 

  1. What form of energy is output from a solar cell?
    Answer: Electrical

 

  1. What is the value of 1 electron volt in joules?
    Answer: 1.6 × 10⁻¹⁹

 

  1. Which energy conversion occurs in an electric motor?
    Answer: Mechanical

 

  1. What is the work done when there is no displacement?
    Answer: Zero

 

  1. What type of energy is stored in a battery?
    Answer: Chemical

 

  1. What kind of energy does a pendulum have at its lowest point?
    Answer: Kinetic

 

  1. What is the SI unit of energy?
    Answer: Joule

 

  1. What form of energy does steam contain?
    Answer: Heat

 

  1. What kind of energy is petrol an example of?
    Answer: Chemical

 

  1. What energy form does moving air represent?
    Answer: Wind

 

  1. What type of kinetic energy is present in a spinning wheel?
    Answer: Rotational

 

  1. What energy does a stone possess while falling?
    Answer: Kinetic

 

  1. What energy does a book on a shelf have?
    Answer: Potential

 

  1. What is the value of 1 calorie in joules?
    Answer: 4.18

 

  1. What is the result when force and displacement are perpendicular?
    Answer: Zero

 

  1. What is the type of energy in a running car?
    Answer: Kinetic

 

  1. What is the energy transformation in a battery?
    Answer: Electrical

 

  1. What type of energy is conserved in free fall?
    Answer: Mechanical

 

  1. What is the nature of work—scalar or vector?
    Answer: Scalar

 

  1. What quantity equals mass × gravity × height?
    Answer: Potential

 

  1. What quantity equals ½ × mass × velocity²?
    Answer: Kinetic

 

  1. What is the energy unit used in thermodynamics?
    Answer: Calorie

 

  1. What is the term for energy stored in deformed solids?
    Answer: Elastic

 

  1. What is the energy type produced by friction?
    Answer: Heat

 

  1. What is the energy transformation in a loudspeaker?
    Answer: Sound

 

  1. What is the energy transformation in a generator?
    Answer: Electrical

 

  1. What is the energy in a compressed spring?
    Answer: Elastic

 

  1. What is the energy of flowing water?
    Answer: Hydro

 

  1. What quantity remains constant in ideal free fall?
    Answer: Energy

 

  1. What energy is associated with linear motion?
    Answer: Translational

 

  1. What is the form of kinetic energy in vibrating objects?
    Answer: Vibrational

ICSE - Grade 10 - Physics

All Chapters

  • Chapter 1 – Force
  • Chapter 2 – Work, Energy and Power
  • Chapter 3 – Machines
  • Chapter 4 – Refraction of Light at Plane Surfaces
  • Chapter 5 – Refraction through Lens
  • Chapter 6 – Spectrum
  • Chapter 7 – Sound
  • Chapter 8 – Current Electricity
  • Chapter 9 – Electrical Power and Household Circuits
  • Chapter 10 – Electro-magnetism
  • Chapter 11 – Calorimetry
  • Chapter 12 – Radioactivity

ICSE - Grade 10 - Chemistry

All Chapters

  • Chapter 1 The Language of Chemistry
  • Chapter 2 Chemical Changes and Reactions
  • Chapter 3 Water
  • Chapter 4 Atomic Structure and Chemical Bonding
  • Chapter 5 The periodic table
  • Chapter 6 Study of the first Element Hydrogen
  • Chapter 7 Study of Gas laws
  • Chapter 8 Atmospheric Pollution

ICSE - Grade 10 - Mathematics

All Chapters

  • Chapter 1 Rational and Irrational Numbers
  • Chapter 2 Compound Interest [Without Using Formula]
  • Chapter 3 Compound Interest [Using Formula]
  • Chapter 4 Expansions
  • Chapter 5 Factorisation
  • Chapter 6 Simultaneous Equations
  • Chapter 7 Indices
  • Chapter 8 Logarithms
  • Chapter 9 Triangles
  • Chapter 10 Isosceles Triangles
  • Chapter 11 Inequalities
  • Chapter 12 Midpoint and Its Converse
  • Chapter 13 Pythagoras Theorem
  • Chapter 14 Rectilinear Figures
  • Chapter 15 Construction of Polygons
  • Chapter 16 Area Theorems
  • Chapter 17 Circle
  • Chapter 18 Statistics
  • Chapter 19 Mean and Median
  • Chapter 20 Area and Perimeter of Plane Figures
  • Chapter 21 Solids
  • Chapter 22 Trigonometrical Ratios
  • Chapter 23 Trigonometrical Ratios of Standard Angles
  • Chapter 24 Solutions of Right Triangles
  • Chapter 25 Complementary Angles
  • Chapter 26 Coordinate Geometry
  • Chapter 27 Graphical Solution
  • Chapter 28 Distance Formula

ICSE - Grade 10 - Biology

All Chapters

  • Chapter 1 Introducing Biology
  • Chapter 2 Cell: The Unit Of Life
  • Chapter 3 Tissues: Plant And Animal Tissue
  • Chapter 4 The Flower
  • Chapter 5 Pollination and Fertilization
  • Chapter 6 Seeds: Structure and Germination
  • Chapter 7 Respiration in Plants
  • Chapter 8 Five Kingdom Classification
  • Chapter 9 Economic Importance of Bacteria and Fungi
  • Chapter 10 Nutrition
  • Chapter 11 Digestive system
  • Chapter 12 Skeleton: Movement and Locomotion
  • Chapter 13 Skin: The Jack of all trades
  • Chapter 14 The Respiratory System
  • Chapter 15 Hygiene: [A key to Healthy Life]
  • Chapter 16 Diseases: Cause and Control
  • Chapter 17 Aids to Health
  • Chapter 18 Health Organizations
  • Chapter 19 Waste Generation and Management

ICSE - Grade 10 - History

All Chapters

  • Chapter 1 – The Harappan Civilisation
  • Chapter 2 – The Vedic Period
  • Chapter 3 – Jainism and Buddhism
  • Chapter 4 – The Mauryan Empire
  • History — Chapter 5
    The Sangam Age
  • Chapter 6 – The Age of the Guptas
  • Chapter 7 – Medieval India — (A) The Cholas
  • Chapter 8 – Medieval India — (B) The Delhi Sultanate
  • Chapter 9 – Medieval India — (C) The Mughal Empire
  • Chapter 10 – Medieval India — (D) Composite Culture
  • Chapter 11 – The Modern Age in Europe — (A) Renaissance
  • Chapter 12 – The Modern Age in Europe — (B) Reformation
  • Chapter 13 – The Modern Age in Europe — (C) Industrial Revolution
  •  

ICSE - Grade 10 - Civics

All Chapters

  • Chapter 1: Our Constitution
  • Chapter 2: Salient Features of the Constitution — I
  • Chapter 3: Salient Features of the
  • Constitution — II
  • Chapter 4: Elections
  • Chapter 5: Local Self-Government — Rural
  • Chapter 6: Local Self-Government — Urban
  •  

ICSE - Grade 10 - Geography

All Chapters

  • Ch 1 – Earth as a Planet
    Ch 2 – Geographic Grid: Latitudes and Longitudes
    Ch 3 – Rotation and Revolution
    Ch 4 – Earth’s Structure
    Ch 5 – Landforms of the Earth
    Ch 6 – Rocks
    Ch 7 – Volcanoes
    Ch 8 – Earthquakes
    Ch 9 – Weathering
    Ch 10 – Denudation
    Ch 11 – Hydrosphere
    Ch 12 – Composition and Structure of the Atmosphere
    Ch 13 – Insolation
    Ch 14 – Atmospheric Pressure and Winds
    Ch 15 – Humidity
    Ch 16 – Pollution
    Ch 17 – Sources of Pollution
    Ch 18 – Effects of Pollution
    Ch 19 – Preventive Measures
    Ch 20 – Natural Regions of the World

ICSE Grade 10

3500/-
  • All Subjects
  • Free Study Material
  • MCQ Tests
  • Theory Tests
  • Assignments
Register

Find the Odd Man Out

  1. Work, Power, Energy, Velocity
    Answer: Velocity
    Explanation: Others are scalar quantities; velocity is a vector.

 

  1. Joule, Watt, Erg, Calorie
    Answer: Watt
    Explanation: Watt is a unit of power; others are units of energy or work.

 

  1. Kinetic energy, Potential energy, Sound energy, Speed
    Answer: Speed
    Explanation: Speed is not a form of energy.

 

  1. Calorie, Joule, Erg, Newton
    Answer: Newton
    Explanation: Newton is a unit of force; others are units of energy.

 

  1. Displacement, Force, Energy, Work
    Answer: Displacement
    Explanation: Displacement is not a scalar; others are scalar physical quantities.

 

  1. Battery, Generator, Solar panel, Electric motor
    Answer: Electric motor
    Explanation: Others convert energy to electrical form; electric motor converts electrical to mechanical.

 

  1. Translational energy, Rotational energy, Heat energy, Vibrational energy
    Answer: Heat energy
    Explanation: Others are forms of mechanical kinetic energy.

 

  1. mgh, ½mv², F × S × cosθ, Q = mcΔT
    Answer: Q = mcΔT
    Explanation: It’s the formula for heat energy; others are for mechanical energy and work.

 

  1. Horsepower, Watt, Newton, Kilowatt
    Answer: Newton
    Explanation: Newton is a unit of force; others are units of power.

 

  1. Sound, Light, Wind, Momentum
    Answer: Momentum
    Explanation: Others are forms of energy; momentum is not.

 

  1. Kilojoule, Joule, Kilowatt, Erg
    Answer: Kilowatt
    Explanation: Kilowatt is a unit of power; others are units of energy.

 

  1. Elastic, Gravitational, Nuclear, Magnetic
    Answer: Magnetic
    Explanation: Others are types of potential energy.

 

  1. Potential energy, Chemical energy, Nuclear energy, Acceleration
    Answer: Acceleration
    Explanation: Acceleration is not a form of energy.

 

  1. Force, Mass, Energy, Power
    Answer: Mass
    Explanation: Others are derived physical quantities; mass is a fundamental quantity.

 

  1. Chemical → Electrical, Heat → Mechanical, Sound → Pressure, Mechanical → Electrical
    Answer: Sound → Pressure
    Explanation: Not an energy transformation; pressure is not a form of energy.

 

  1. Kinetic energy, Potential energy, Displacement, Work
    Answer: Displacement
    Explanation: Displacement is not a form of energy or work.

 

  1. Calorie, Erg, kWh, Ampere
    Answer: Ampere
    Explanation: Ampere is a unit of current; others are energy units.

 

  1. Friction, Heat, Work, Gravity
    Answer: Gravity
    Explanation: Others involve conversion or loss of energy; gravity is a force.

 

  1. Elastic energy, Sound energy, Translational energy, Kinetic energy
    Answer: Sound energy
    Explanation: Others are mechanical; sound is non-mechanical.

 

  1. Rotational, Electrical, Vibrational, Translational
    Answer: Electrical
    Explanation: Others are types of mechanical energy.

 

  1. Kinetic energy, Work done, Potential energy, Time
    Answer: Time
    Explanation: Others are energy-related; time is a base quantity.

 

  1. Force, Speed, Power, Work
    Answer: Speed
    Explanation: Speed is not directly related to energy or work.

 

  1. Calorie, kWh, Ampere, Joule
    Answer: Ampere
    Explanation: Ampere is a unit of current, others are energy units.

 

  1. Loudspeaker, Battery, Solar panel, Generator
    Answer: Loudspeaker
    Explanation: Others convert energy to electricity; loudspeaker converts to sound.

 

  1. Watt, Kilowatt, Newton, Horsepower
    Answer: Newton
    Explanation: Newton is a unit of force, others are power.

 

  1. Mechanical, Chemical, Potential, Work
    Answer: Work
    Explanation: Others are types of energy; work is energy transferred.

 

  1. Velocity, Displacement, Distance, Heat
    Answer: Heat
    Explanation: Others are motion-related quantities; heat is not.

 

  1. Solar, Nuclear, Wind, Thermometer
    Answer: Thermometer
    Explanation: Others are energy sources; thermometer is not.

 

  1. Electricity, Magnetism, Gravity, Work
    Answer: Work
    Explanation: Others are forces or fields; work is energy transferred.

 

  1. Erg, Calorie, Kilojoule, Kilogram
    Answer: Kilogram
    Explanation: Kilogram is a unit of mass; others are energy.

 

  1. Electric motor, Turbine, Battery, Hammer
    Answer: Hammer
    Explanation: Others are machines that convert energy; hammer is a tool.

 

  1. ½mv², mgh, F = ma, P = W/t
    Answer: F = ma
    Explanation: Others relate to energy and power; F = ma is Newton’s law.

 

  1. Waterfall, Pendulum, Windmill, Oven
    Answer: Oven
    Explanation: Others show mechanical energy; oven uses thermal.

 

  1. Work, Energy, Heat, Displacement
    Answer: Displacement
    Explanation: Others relate to energy; displacement is motion.

 

  1. Calorie, Joule, Erg, Meter
    Answer: Meter
    Explanation: Meter is a unit of length; others are for energy.

 

  1. Speed, Velocity, Distance, Power
    Answer: Power
    Explanation: Others are motion-related; power is energy/time.

 

  1. Current, Voltage, Resistance, Potential energy
    Answer: Potential energy
    Explanation: Others are electrical; potential energy is mechanical.

 

  1. Force, Power, Mass, Energy
    Answer: Mass
    Explanation: Others are derived quantities; mass is base.

 

  1. Newton, Pascal, Watt, Ampere
    Answer: Watt
    Explanation: Others are force, pressure, and current; watt is power.

 

  1. Solar, Light, Magnetic, Inertia
    Answer: Inertia
    Explanation: Others are forms of energy; inertia is a property.

 

  1. P = W/t, W = F × S, F = m × a, V = I × R
    Answer: V = I × R
    Explanation: It is from electricity; others are from mechanics.

 

  1. Spring, Stone, Battery, Wire
    Answer: Wire
    Explanation: Others store or convert energy; wire does not by itself.

 

  1. Vibrational energy, Rotational energy, Elastic energy, Light energy
    Answer: Light energy
    Explanation: Others are mechanical; light is electromagnetic.

 

  1. Force, Power, Energy, Temperature
    Answer: Temperature
    Explanation: Others involve work and energy; temperature is thermal property.

 

  1. Generator, Solar panel, Loudspeaker, Electric motor
    Answer: Loudspeaker
    Explanation: It converts electrical to sound; others convert energy types to/from mechanical/electrical.

 

  1. Water, Wind, Uranium, Thermometer
    Answer: Thermometer
    Explanation: Others are energy sources; thermometer is a measuring instrument.

 

  1. Kilowatt, Kilogram, Kilojoule, Calorie
    Answer: Kilogram
    Explanation: Kilogram is mass; others are energy/power.

 

  1. Translational, Rotational, Displacement, Vibrational
    Answer: Displacement
    Explanation: Others are types of kinetic energy; displacement is not.

 

  1. Sound, Nuclear, Mechanical, Density
    Answer: Density
    Explanation: Others are energy forms; density is a property.

 

  1. mgh, ½mv², P = F/A, W = F × S
    Answer: P = F/A
    Explanation: It is pressure formula; others relate to energy or work.

Match the Pair

Set 1 – Units and Quantities

Column A

  1. Work
  2. Energy
  3. Power
  4. Force
  5. Acceleration

Column B
 a) Watt
 b) Newton
 c) Joule
 d) m/s²
 e) Calorie

Answers:
 1 → c
 2 → e
 3 → a
 4 → b
 5 → d



Set 2 – Formulas

Column A

  1. Kinetic energy
  2. Power
  3. Work
  4. Potential energy
  5. Work-energy theorem

Column B
 a) W = F × S × cosθ
 b) W = Kf – Ki
 c) K = ½ mv²
 d) P = W / t
 e) U = mgh

Answers:
 1 → c
 2 → d
 3 → a
 4 → e
 5 → b



Set 3 – Types of Energy

Column A

  1. Energy due to motion
  2. Energy due to position
  3. Energy in stretched spring
  4. Energy in food
  5. Energy in sunlight

Column B
 a) Solar energy
 b) Chemical energy
 c) Elastic potential energy
 d) Kinetic energy
 e) Potential energy

Answers:
 1 → d
 2 → e
 3 → c
 4 → b
 5 → a



Set 4 – Energy Conversions

Column A

  1. Generator
  2. Electric bulb
  3. Battery
  4. Loudspeaker
  5. Solar cell

Column B
 a) Chemical → Electrical
 b) Mechanical → Electrical
 c) Electrical → Sound
 d) Electrical → Heat and Light
 e) Light → Electrical

Answers:
 1 → b
 2 → d
 3 → a
 4 → c
 5 → e




Set 5 – Units and Equivalents

Column A

  1. 1 kilowatt
  2. 1 H.P.
  3. 1 kilowatt-hour
  4. 1 calorie
  5. 1 eV

Column B
 a) 746 W
 b) 3.6 × 10⁶ J
 c) 1.6 × 10⁻¹⁹ J
 d) 4.18 J
 e) 1000 W

Answers:
 1 → e
 2 → a
 3 → b
 4 → d
 5 → c



Set 6 – Types of Motion and Kinetic Energy

Column A

  1. Car on road
  2. Spinning top
  3. Vibrating string
  4. Ball rolling
  5. Satellite orbiting

Column B
 a) Rotational + Translational KE
 b) Translational KE
 c) Rotational KE
 d) Vibrational KE
 e) Rotational + Gravitational PE

Answers:
 1 → b
 2 → c
 3 → d
 4 → a
 5 → e



Set 7 – Zero Work Cases

Column A

  1. Holding a bag stationary
  2. Circular motion at constant speed
  3. Perpendicular force and displacement
  4. No displacement
  5. Displacement at 90° to force

Column B
 a) θ = 90°
 b) Centripetal force is perpendicular to motion
 c) Displacement = 0
 d) No motion
 e) No work done

Answers:
 1 → d
 2 → b
 3 → a
 4 → c
 5 → e



Set 8 – Work, Power, and Energy Characteristics

Column A

  1. Scalar quantity
  2. Measured in Watt
  3. Work done against gravity
  4. Rate of energy consumption
  5. Product of force and displacement

Column B
 a) Power
 b) Scalar
 c) Work
 d) Joule
 e) mgh

Answers:
 1 → b
 2 → a
 3 → e
 4 → a
 5 → c



Set 9 – Principle and Applications

Column A

  1. Conservation of energy
  2. Energy of freely falling object
  3. Energy of pendulum at mean position
  4. Energy at highest point of pendulum
  5. Conversion of PE to KE

Column B
 a) PE = mgh
 b) Total energy = constant
 c) Happens in free fall
 d) KE = max
 e) PE = max

Answers:
 1 → b
 2 → b
 3 → d
 4 → e
 5 → c



Set 10 – Physical Quantities and Symbols

Column A

  1. Displacement
  2. Force
  3. Mass
  4. Velocity
  5. Acceleration

Column B
 a) v
 b) a
 c) m
 d) F
 e) S

Answers:
 1 → e
 2 → d
 3 → c
 4 → a
 5 → b

Short Answer Questions  

  1. What is the SI unit of work?
    Answer: The SI unit of work is joule.

 

  1. Define power.
    Answer: Power is the rate at which work is done.

 

  1. What is meant by energy?
    Answer: Energy is the capacity to do work.

 

  1. What is the SI unit of power?
    Answer: The SI unit of power is watt.

 

  1. What is the commercial unit of energy?
    Answer: The commercial unit of energy is kilowatt-hour.

 

  1. Define 1 joule of work.
    Answer: 1 joule of work is done when a force of 1 newton displaces an object by 1 metre in its direction.

 

  1. Write the formula for kinetic energy.
    Answer: Kinetic energy = ½ mv².

 

  1. Write the formula for potential energy.
    Answer: Potential energy = mgh.

 

  1. Define 1 watt of power.
    Answer: Power is 1 watt when 1 joule of work is done in 1 second.

 

  1. What is work done when force and displacement are perpendicular?
    Answer: Work done is zero.

 

  1. When is work said to be negative?
    Answer: Work is negative when force and displacement are in opposite directions.

 

  1. What is meant by 1 kilowatt-hour?
    Answer: 1 kilowatt-hour is the energy consumed when 1 kilowatt power is used for 1 hour.

 

  1. State the law of conservation of energy.
    Answer: Energy can neither be created nor destroyed, it only transforms from one form to another.

 

  1. Give one example of kinetic energy.
    Answer: A moving car possesses kinetic energy.

 

  1. Give one example of potential energy.
    Answer: Water stored in a dam has potential energy.

 

  1. What is mechanical energy?
    Answer: Mechanical energy is the sum of kinetic and potential energy.

 

  1. Give one example of electrical energy.
    Answer: A battery powering a bulb produces electrical energy.

 

  1. What is 1 horsepower equal to in watts?
    Answer: 1 horsepower = 746 watts.

 

  1. Name the energy transformation in an electric motor.
    Answer: Electrical energy is converted into mechanical energy.

 

  1. Name the energy transformation in a solar panel.
    Answer: Solar energy is converted into electrical energy.

 

  1. When is work said to be done?
    Answer: Work is done when a force causes displacement in its direction.

 

  1. Can energy be created?
    Answer: No, energy cannot be created.

 

  1. What does the area under a force-displacement graph represent?
    Answer: It represents work done.

 

  1. What is the relation between work and energy?
    Answer: Energy is the capacity to do work.

 

  1. What is the energy possessed by a stretched spring?
    Answer: Elastic potential energy.

 

  1. Name a device that converts sound energy into electrical energy.
    Answer: Microphone.

 

  1. Name a device that converts electrical energy into sound energy.
    Answer: Loudspeaker.

 

  1. Name a device that converts mechanical energy into electrical energy.
    Answer: Generator.

 

  1. Name the type of energy possessed by a flying bird.
    Answer: Both kinetic and potential energy.

 

  1. What is the unit of energy in CGS system?
    Answer: Erg.

 

  1. Define 1 kilowatt.
    Answer: 1 kilowatt is equal to 1000 watts.

 

  1. Write the expression for power in terms of work and time.
    Answer: Power = Work / Time.

 

  1. How is kinetic energy affected if mass is doubled?
    Answer: Kinetic energy becomes double if velocity remains the same.

 

  1. How is kinetic energy affected if velocity is doubled?
    Answer: Kinetic energy becomes four times.

 

  1. What kind of energy does a body possess at the highest point of vertical motion?
    Answer: Potential energy.

 

  1. What kind of energy does a body possess just before hitting the ground during free fall?
    Answer: Maximum kinetic energy.

 

  1. Name a renewable source of energy.
    Answer: Solar energy.

 

  1. Give the relation between kilowatt-hour and joule.
    Answer: 1 kilowatt-hour = 3.6 × 10⁶ joules.

 

  1. What is the work done by gravity on a horizontally moving object?
    Answer: Zero.

 

  1. What is the amount of work done when there is no displacement?
    Answer: Zero.

 

  1. Which type of energy does flowing water possess?
    Answer: Kinetic energy.

 

  1. What kind of energy is stored in coal and petroleum?
    Answer: Chemical energy.

 

  1. Name one factor on which potential energy depends.
    Answer: Height of the object from the ground.

 

  1. Name one factor on which kinetic energy depends.
    Answer: Velocity of the object.

 

  1. What is the unit of power used in electricity bills?
    Answer: Kilowatt-hour.

 

  1. Why is work done zero when a person carries a load on a level road?
    Answer: Because displacement is perpendicular to the direction of force (vertical).

 

  1. Define energy transformation.
    Answer: It is the conversion of energy from one form to another.

 

  1. State one condition for work to be negative.
    Answer: Work is negative when force acts opposite to displacement.

 

  1. Name the physical quantity that remains constant during free fall (ignoring air resistance).
    Answer: Mechanical energy.

 

  1. What is the energy transformation in an electric bulb?
    Answer: Electrical energy is converted to light and heat energy.

Puzzles

  1. I am a force’s best friend when there’s motion in my direction. Without me, no energy flows. What am I?
    Answer: Work

 

  1. I’m the reason your mobile lights up and your fan spins. I come in many forms and never die. What am I?
    Answer: Energy

 

  1. You can’t see me, but when things fall, I take over. I increase as height decreases. What am I?
    Answer: Kinetic Energy

 

  1. I stay quiet when there’s no motion, but when things start to move, I speak loudly in joules. Who am I?
    Answer: Work Done

 

  1. I vanish the moment friction appears. I am the sum of two energies. What am I?
    Answer: Mechanical Energy

 

  1. My value rises when you climb a hill. I am stored, silent, and waiting. What am I?
    Answer: Potential Energy

 

  1. Two people lift boxes. One takes 2 minutes, the other 4. Who used more power and why?
    Answer: The one who took 2 minutes; because power = work/time, and time is less.

 

  1. I’m measured in watts, but my bigger cousin lives in electric bills. What am I?
    Answer: Power

 

  1. Which energy form is in food, fuel, and your muscles?
    Answer: Chemical Energy

 

  1. I push a box 5 meters north. Gravity helps?
    Answer: No; gravity acts downward, not along displacement.

 

  1. What remains constant when an object falls freely (ignoring air)?
    Answer: Mechanical Energy

 

  1. I cause motion but have no mass. I’m invisible but powerful. What am I?
    Answer: Energy

 

  1. What increases 4 times if speed doubles?
    Answer: Kinetic Energy

 

  1. I’m the energy you pay for at the end of the month. I’m bigger than joules. What am I?
    Answer: Kilowatt-hour

 

  1. What kind of work is done by friction?
    Answer: Negative Work

 

  1. A car engine does more work in less time. What’s high in this case?
    Answer: Power

 

  1. If I stand still with a load, am I working (physically)?
    Answer: No, work done = 0

 

  1. What energy does a hammer possess before striking?
    Answer: Kinetic Energy

 

  1. The higher I go, the more I store, but I fall, I disappear. Who am I?
    Answer: Potential Energy

 

  1. I convert food to movement. Which energy transformation is this?
    Answer: Chemical to Mechanical

 

  1. What do you call energy that flows in wires?
    Answer: Electrical Energy

 

  1. A ball falls from a height. At midpoint, what energies are present?
    Answer: Both potential and kinetic energy

 

  1. A girl climbs stairs slowly. A boy runs. Who uses more power?
    Answer: The boy

 

  1. What is zero when displacement is zero?
    Answer: Work

 

  1. I can’t be destroyed, but I change form often. What principle am I?
    Answer: Law of Conservation of Energy

 

  1. What energy runs a hydroelectric plant?
    Answer: Gravitational Potential Energy

 

  1. A falling object accelerates. Which energy is growing?
    Answer: Kinetic Energy

 

  1. Two boys lift same load; one does it faster. What differs?
    Answer: Power

 

  1. I’m a scalar and can be negative. What am I?
    Answer: Work

 

  1. What energy causes a fan to rotate?
    Answer: Electrical Energy

 

  1. I do work but I don’t move myself. I’m a concept, not a tool. What am I?
    Answer: Force

 

  1. When is work done maximum with respect to angle?
    Answer: When angle is 0° (force and displacement same direction)

 

  1. I’m the dot product of two vectors. What quantity am I?
    Answer: Work

 

  1. A bulb glows. Name the energy transformation.
    Answer: Electrical to Light (and Heat)

 

  1. An archer stretches a bow. What energy is stored?
    Answer: Elastic Potential Energy

 

  1. If mass increases, what happens to P.E. at same height?
    Answer: Increases

 

  1. A mass is dropped. What’s its P.E. just before it touches ground?
    Answer: Zero

 

  1. A man lifts a load, but slips — still does work?
    Answer: Yes, if there’s displacement before slipping

 

  1. You see a glowing bulb. Where was the energy stored before?
    Answer: In a battery or power supply as chemical or electrical energy

 

  1. Why does a falling apple gain speed?
    Answer: Gravity converts potential energy to kinetic

 

  1. Which force does no work on a satellite in circular orbit?
    Answer: Gravitational force (perpendicular to displacement)

 

  1. You lift a box straight up. What kind of work is done?
    Answer: Positive Work

 

  1. A battery dies out. What energy got used?
    Answer: Chemical Energy

 

  1. What energy makes a pendulum swing?
    Answer: Interchange of potential and kinetic energy

 

  1. I’m equal to 1 newton × 1 meter. What am I?
    Answer: 1 Joule

 

  1. What does your body use to walk or lift things?
    Answer: Chemical Energy

 

  1. Name the device that converts mechanical energy to electrical energy.
    Answer: Generator

 

  1. I am energy in motion. What am I?
    Answer: Kinetic Energy

 

  1. When is total mechanical energy conserved?
    Answer: In absence of friction or external forces

 

  1. I’m always part of energy conversion but often lost. What am I?
    Answer: Heat Energy

Difference Between:

  1. Difference between Work and Power
    Answer:
  • Work is the product of force and displacement.
  • Power is the rate of doing work.

 

  1. Difference between Work and Energy
    Answer:
  • Work is the result of applying force over a distance.
  • Energy is the capacity to do work.

 

  1. Difference between Potential Energy and Kinetic Energy
    Answer:
  • Potential energy is stored due to position or configuration.
  • Kinetic energy is possessed due to motion.

 

  1. Difference between Positive Work and Negative Work
    Answer:
  • Positive work is when force and displacement are in the same direction.
  • Negative work is when force and displacement are in opposite directions.

 

  1. Difference between Power and Energy
    Answer:
  • Power is the rate of energy transfer or work done per unit time.
  • Energy is the total work done or capacity to do work.

 

  1. Difference between Commercial Unit of Energy and SI Unit of Energy
    Answer:
  • Commercial unit is kilowatt-hour (kWh).
  • SI unit is joule (J).

 

  1. Difference between Watt and Kilowatt
    Answer:
  • Watt is a smaller unit (1 W = 1 J/s).
  • Kilowatt is 1000 watts (1 kW = 1000 W).

 

  1. Difference between Horsepower and Watt
    Answer:
  • Horsepower is a traditional unit used for engines (1 HP = 746 W).
  • Watt is the SI unit of power.

 

  1. Difference between Energy Transformation and Energy Conservation
    Answer:
  • Energy transformation is the change from one form to another.
  • Energy conservation is the principle that total energy remains constant.

 

  1. Difference between Mechanical Energy and Electrical Energy
    Answer:
  • Mechanical energy includes kinetic and potential energy.
  • Electrical energy is due to movement of electric charges.

 

  1. Difference between Scalar and Vector Quantities (in context of Work and Force)
    Answer:
  • Work is scalar; it has magnitude only.
  • Force is vector; it has both magnitude and direction.

 

  1. Difference between Instantaneous Power and Average Power
    Answer:
  • Instantaneous power is power at a specific instant.
  • Average power is total work done divided by total time.

 

  1. Difference between Mass and Weight (in energy context)
    Answer:
  • Mass is the quantity of matter (used in energy calculations).
  • Weight is force due to gravity (used in work = weight × height).

 

  1. Difference between Renewable and Non-renewable Energy Sources
    Answer:
  • Renewable sources are naturally replenished (e.g., solar, wind).
  • Non-renewable sources are finite (e.g., coal, oil).

 

  1. Difference between Gravitational Potential Energy and Elastic Potential Energy
    Answer:
  • Gravitational potential energy is due to height.
  • Elastic potential energy is due to deformation (like spring/stretch).

 

  1. Difference between Zero Work and Negative Work
    Answer:
  • Zero work occurs when displacement is zero or perpendicular to force.
  • Negative work occurs when displacement is opposite to force.

 

  1. Difference between Energy Stored and Energy Utilized
    Answer:
  • Energy stored is available but not in use (e.g., in fuel).
  • Energy utilized is already converted and used for work.

 

  1. Difference between Work Done by Gravity and Work Done Against Gravity
    Answer:
  • Work by gravity is positive during free fall.
  • Work against gravity is done when lifting an object upward.

 

  1. Difference between Kinetic Energy and Work Done
    Answer:
  • Kinetic energy is energy of motion.
  • Work done is energy transferred to an object via force and displacement.

 

  1. Difference between Force and Energy
    Answer:
  • Force causes an object to accelerate or change direction.
  • Energy is the capacity to perform work, possibly using force.

Assertion and Reason

Instructions for Answer Format:
 Choose from the options:
 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: Work done is zero when force and displacement are perpendicular.
    Reason: Cos 90° = 0
     Answer: A

 


  1. Assertion: A moving object possesses potential energy.
    Reason: Potential energy depends on motion.
     Answer: C

 


  1. Assertion: Work is a scalar quantity.
    Reason: It is the product of force and displacement.
     Answer: B

 


  1. Assertion: Energy is the capacity to do work.
    Reason: Without energy, no object can be displaced.
     Answer: A

 


  1. Assertion: Power is the rate at which work is done.
    Reason: Power = Force × displacement
     Answer: C

 


  1. Assertion: Work done by friction is negative.
    Reason: Friction always acts in the direction of motion.
     Answer: C

 


  1. Assertion: The SI unit of work is watt.
    Reason: Watt is the unit of power, not work.
     Answer: D

 


  1. Assertion: 1 kilowatt = 1000 watts.
    Reason: ‘Kilo’ stands for thousand.
     Answer: A

 


  1. Assertion: A body falling freely under gravity gains potential energy.
    Reason: Height of the body increases.
     Answer: D

 


  1. Assertion: A book resting on a table has potential energy.
    Reason: It is at a height from the ground.
     Answer: A

 


  1. Assertion: A body at rest can do work.
    Reason: It may possess potential energy.
     Answer: A

 


  1. Assertion: Work is done when a body moves under the influence of force.
    Reason: Work requires force and displacement.
     Answer: A

 


  1. Assertion: Kinetic energy of a body depends on its velocity.
    Reason: Kinetic energy = ½ mv²
     Answer: A

 


  1. Assertion: A moving car has only kinetic energy.
    Reason: It has no potential energy.
     Answer: C

 


  1. Assertion: The energy stored in a compressed spring is kinetic energy.
    Reason: Spring is deformed, not moving.
     Answer: D

 


  1. Assertion: The unit of energy and work are the same.
    Reason: Energy is the capacity to do work.
     Answer: A

 


  1. Assertion: Force is required to do work.
    Reason: Displacement is not necessary for work.
     Answer: C

 


  1. Assertion: 1 joule = 10⁷ ergs
    Reason: 1 N = 10⁵ dyne and 1 m = 10² cm
     Answer: A

 


  1. Assertion: A man carrying a load on a frictionless surface does positive work.
    Reason: There is no friction.
     Answer: C

 


  1. Assertion: Power depends only on the amount of work done.
    Reason: Power = Work / Time
     Answer: C

 


  1. Assertion: Potential energy is a type of mechanical energy.
    Reason: It is energy due to position.
     Answer: A

 


  1. Assertion: Sound energy is a form of mechanical energy.
    Reason: It is produced due to the vibration of particles.
     Answer: A

 


  1. Assertion: Energy cannot be destroyed.
    Reason: Energy follows the conservation principle.
     Answer: A

 


  1. Assertion: A rolling ball has only translational kinetic energy.
    Reason: It does not rotate.
     Answer: C

 


  1. Assertion: Work is done when a person holds a heavy bag without moving.
    Reason: There is no displacement.
     Answer: D

 


  1. Assertion: Kilowatt-hour is a unit of power.
    Reason: It is energy consumed per second.
     Answer: D

 


  1. Assertion: 1 calorie = 4.18 joules.
    Reason: Both are units of energy.
     Answer: A

 


  1. Assertion: Friction converts kinetic energy into heat energy.
    Reason: Friction opposes motion and generates heat.
     Answer: A

 


  1. Assertion: The gravitational potential energy of a body increases as it falls.
    Reason: Height is increasing during fall.
     Answer: D

 


  1. Assertion: The area under force-displacement graph gives work.
    Reason: Work = Force × Displacement
     Answer: A

 


  1. Assertion: The total energy in a pendulum remains constant.
    Reason: Mechanical energy is conserved.
     Answer: A

 


  1. Assertion: A pendulum has maximum kinetic energy at extreme position.
    Reason: Speed is maximum at that point.
     Answer: D

 


  1. Assertion: Energy stored in fuel is chemical energy.
    Reason: Fuel undergoes chemical reactions to release energy.
     Answer: A

 


  1. Assertion: Power has no direction.
    Reason: Power is a scalar quantity.
     Answer: A

 


  1. Assertion: Work done can be positive or negative.
    Reason: It depends on the angle between force and displacement.
     Answer: A

 


  1. Assertion: A man pushing a wall does work.
    Reason: He applies force.
     Answer: C

 


  1. Assertion: 1 horsepower = 1000 W
    Reason: Horsepower is a smaller unit than watt.
     Answer: D

 


  1. Assertion: Energy stored in a dam is potential energy.
    Reason: Water is at a height.
     Answer: A

 


  1. Assertion: The efficiency of a machine is measured in kilowatt.
    Reason: Kilowatt is the unit of power.
     Answer: D

 


  1. Assertion: A body must move to have kinetic energy.
    Reason: Kinetic energy depends on velocity.
     Answer: A

 


  1. Assertion: Watt is a derived unit.
    Reason: It is derived from joule and second.
     Answer: A

 


  1. Assertion: A body with mass but no speed has kinetic energy.
    Reason: Kinetic energy depends only on mass.
     Answer: C

 


  1. Assertion: Mechanical energy includes only kinetic energy.
    Reason: Mechanical energy includes potential and kinetic energy.
     Answer: D

 


  1. Assertion: A solar cell converts light energy to electrical energy.
    Reason: It uses photovoltaic effect.
     Answer: A

 


  1. Assertion: The energy possessed by compressed gas is elastic potential energy.
    Reason: It has the ability to do work due to deformation.
     Answer: A

 


  1. Assertion: In ideal conditions, total mechanical energy is conserved.
    Reason: No energy is lost to friction or air resistance.
     Answer: A

 


  1. Assertion: Heat is a form of energy.
    Reason: It causes temperature change and can do work.
     Answer: A

 


  1. Assertion: Power is energy stored in a body.
    Reason: Power is the rate at which energy is used.
     Answer: C

 


  1. Assertion: Electrical energy is a mechanical energy.
    Reason: Both can do work.
     Answer: C

 


  1. Assertion: A falling object loses potential energy and gains kinetic energy.
    Reason: Total mechanical energy remains constant.
     Answer: A

True or False

  1. Work is done only when displacement takes place.
    Answer: True

 

  1. Work is a vector quantity.
    Answer: False

 

  1. The SI unit of work is joule.
    Answer: True

 

  1. Power is the total amount of work done.
    Answer: False

 

  1. 1 horsepower is equal to 746 watts.
    Answer: True

 

  1. Energy is the ability to do work.
    Answer: True

 

  1. Joule is the SI unit of energy.
    Answer: True

 

  1. A body at rest has no energy.
    Answer: False

 

  1. Kinetic energy is due to motion.
    Answer: True

 

  1. Potential energy depends on velocity.
    Answer: False

 

  1. The formula for kinetic energy is ½mv².
    Answer: True

 

  1. Work done is always positive.
    Answer: False

 

  1. If a person holds a heavy object without moving, work is done.
    Answer: False

 

  1. Work is said to be zero if displacement is zero.
    Answer: True

 

  1. If force and displacement are perpendicular, work done is zero.
    Answer: True

 

  1. A falling body loses potential energy and gains kinetic energy.
    Answer: True

 

  1. The total mechanical energy in free fall remains constant.
    Answer: True

 

  1. Watt is a unit of energy.
    Answer: False

 

  1. Kilowatt-hour is a unit of power.
    Answer: False

 

  1. 1 kilowatt-hour = 3.6 × 10⁶ joules.
    Answer: True

 

  1. Calorie is a unit used to measure heat.
    Answer: True

 

  1. 1 calorie = 2.18 joules.
    Answer: False

 

  1. 1 eV = 1.6 × 10⁻¹⁹ joules.
    Answer: True

 

  1. Gravitational potential energy is given by mgh.
    Answer: True

 

  1. Power = Work × Time.
    Answer: False

 

  1. In SI, power is measured in watts.
    Answer: True

 

  1. Potential energy is maximum at the mean position of a pendulum.
    Answer: False

 

  1. Kinetic energy is zero at the highest point of pendulum swing.
    Answer: True

 

  1. Work is done when force causes displacement.
    Answer: True

 

  1. A man walking with a bag on his head does no work against gravity.
    Answer: True

 

  1. Energy can be created but not destroyed.
    Answer: False

 

  1. Light energy can be converted to electrical energy.
    Answer: True

 

  1. Loudspeakers convert electrical energy to sound energy.
    Answer: True

 

  1. All forms of energy can be converted into heat.
    Answer: True

 

  1. A generator converts electrical energy to mechanical energy.
    Answer: False

 

  1. A battery stores electrical energy directly.
    Answer: False

 

  1. Solar panels convert solar energy to heat energy.
    Answer: False

 

  1. A compressed spring stores kinetic energy.
    Answer: False

 

  1. The energy of a body in motion is potential energy.
    Answer: False

 

  1. Mechanical energy includes both kinetic and potential energy.
    Answer: True

 

  1. A moving vehicle possesses only rotational energy.
    Answer: False

 

  1. Friction converts mechanical energy to heat energy.
    Answer: True

 

  1. Work is done even if force is applied but there is no displacement.
    Answer: False

 

  1. When displacement is opposite to force, work is negative.
    Answer: True

 

  1. Energy and work have the same SI unit.
    Answer: True

 

  1. The efficiency of a machine can be more than 100%.
    Answer: False

 

  1. A stretched rubber band has elastic potential energy.
    Answer: True

 

  1. An object at ground level has maximum potential energy.
    Answer: False

 

  1. The area under a force-displacement graph gives power.
    Answer: False

 

  1. Scalar product of force and displacement gives work.
    Answer: True

Long Answer Questions

  1. Define work. State its SI unit. What are the conditions for work to be done?
    Answer:
    Work is said to be done when a force is applied on a body and the body is displaced in the direction of the applied force.
     SI unit: Joule.
     Conditions:
  1. A force must be applied.
  2. There must be displacement.
  3. Displacement must have a component in the direction of the force.

 

  1. Explain positive, negative, and zero work with examples.
    Answer:
  • Positive work: When force and displacement are in the same direction. Example: A man pushing a trolley forward.
  • Negative work: When force and displacement are in opposite directions. Example: Work done by friction.
  • Zero work: When displacement is zero or perpendicular to force. Example: Holding a book without moving it.

 

  1. Derive the formula for kinetic energy of a moving body.
    Answer:
    Let a body of mass m move with initial velocity u, and is accelerated by force F over displacement S to reach velocity v.
     From equations of motion:
     v² = u² + 2aS
     Work done = Force × Displacement = F × S
     But F = ma, and from the above:
     S = (v² – u²)/2a
     So W = ma × [(v² – u²)/2a] = m(v² – u²)/2
     If u = 0, then K.E. = ½ mv²

 

  1. What is potential energy? Derive the expression for gravitational potential energy.
    Answer:
    Potential energy is the energy possessed by a body due to its position or configuration.
     If a body of mass m is raised to height h, work is done against gravity.
     Work = Force × Displacement = mgh
     Hence, P.E. = mgh

 

  1. Define 1 joule. How is it related to erg?
    Answer:
    1 joule is the work done when a force of 1 newton displaces a body by 1 metre in the direction of force.
     Relation:
     1 J = 10⁷ erg

 

  1. Define power and state its SI and commercial units.
    Answer:
    Power is the rate at which work is done or energy is transferred.
     SI unit: Watt
     Commercial unit: kilowatt-hour (kWh)

 

  1. Define kilowatt-hour. Derive its relation with joules.
    Answer:
    1 kilowatt-hour is the energy consumed when 1 kilowatt (1000 watts) power is used for 1 hour.
     1 kWh = 1000 × 3600 = 3.6 × 10⁶ J

 

  1. Explain the law of conservation of energy with an example.
    Answer:
    The law states that energy can neither be created nor destroyed, only transformed.
     Example: In a simple pendulum, potential energy converts to kinetic energy and vice versa, but the total mechanical energy remains constant.

 

  1. Write a note on mechanical energy.
    Answer:
    Mechanical energy is the sum of kinetic energy (due to motion) and potential energy (due to position). It is conserved in absence of friction and external forces.

 

  1. A man lifts a box of mass 10 kg to a height of 2 m. Calculate work done.
    Answer:
    Work = mgh = 10 × 9.8 × 2 = 196 J

 

  1. Differentiate between work and energy.
    Answer:
  • Work: It is the transfer of energy due to force and displacement. Unit: Joule
  • Energy: It is the capacity to do work. Unit: Joule

 

  1. Differentiate between energy and power.
    Answer:
  • Energy: Capacity to do work. Unit: Joule
  • Power: Rate of doing work. Unit: Watt

 

  1. Write three differences between potential energy and kinetic energy.
    Answer:

Kinetic Energy

Potential Energy

Due to motion

Due to position

K.E. = ½ mv²

P.E. = mgh

Zero at rest

Can be non-zero at rest

 

  1. Derive the relation: 1 horsepower = 746 watts.
    Answer:
    By definition, 1 horsepower is equivalent to 550 foot-pounds per second.
     In SI: 1 HP = 550 × 0.3048 × 4.448 = 745.7 ≈ 746 W

 

  1. A machine does 1500 J of work in 5 seconds. Calculate its power.
    Answer:
    Power = Work/Time = 1500/5 = 300 W

 

  1. What are the factors affecting potential energy?
    Answer:
  1. Mass of the body (m)
  2. Height above ground (h)
  3. Acceleration due to gravity (g)

 

  1. What are the factors affecting kinetic energy?
    Answer:
  1. Mass of the body (m)
  2. Square of velocity (v²)

 

  1. State the conditions under which mechanical energy is conserved.
    Answer:
    Mechanical energy is conserved when no external force (like friction or air resistance) acts on the system.

 

  1. Explain the energy transformation in a hydroelectric power station.
    Answer:
    Potential energy of water → Kinetic energy → Rotational energy of turbines → Electrical energy via generators.

 

  1. What is the importance of energy in daily life?
    Answer:
    Energy is required for every activity: cooking, lighting, transport, industries, etc. It is fundamental to survival and progress.

 

  1. How is electrical energy calculated using power and time?
    Answer:
    Electrical energy = Power × Time
     In SI: E = P × t (in joules)

 

  1. Describe an experiment to show mechanical energy conservation using a pendulum.
    Answer:
    A pendulum swings back and forth. At the extreme ends, it has maximum P.E. and zero K.E. At the mean position, it has maximum K.E. and zero P.E. Total energy remains constant.

 

  1. Explain why work done is zero in uniform circular motion.
    Answer:
    In circular motion, force (centripetal) is perpendicular to displacement at every point, so work done = 0.

 

  1. A 50 W bulb glows for 2 hours. Calculate energy consumed.
    Answer:
    Energy = Power × Time = 50 × 2 = 100 Wh = 0.1 kWh = 0.1 × 3.6 × 10⁶ = 3.6 × 10⁵ J

 

  1. A body of mass 5 kg is moving at 4 m/s. Calculate its kinetic energy.
    Answer:
    K.E. = ½ × 5 × 4² = ½ × 5 × 16 = 40 J

 

  1. A body of mass 20 kg is raised to a height of 5 m. Find its potential energy.
    Answer:
    P.E. = mgh = 20 × 9.8 × 5 = 980 J

 

  1. Explain with an example how energy is conserved in free fall.
    Answer:
    A falling object loses P.E. and gains K.E. such that total energy (P.E. + K.E.) remains constant throughout the fall.

 

  1. Explain zero work with two examples.
    Answer:
  1. Holding a load without moving.
  2. A satellite revolving in a circular orbit under gravity.

 

  1. What is the work done by gravity on a body thrown vertically upward?
    Answer:
    Negative work, because displacement is upward and force (gravity) is downward.

 

  1. Define efficiency. Write its formula and unit.
    Answer:
    Efficiency = (Useful output energy/Input energy) × 100%
     It has no unit (expressed in %).

 

  1. Explain the transformation of energy in a thermal power plant.
    Answer:
    In a thermal power plant, chemical energy in coal is converted to heat energy, which produces steam. This steam rotates turbines (mechanical energy), which drive generators to produce electrical energy.

 

  1. Write the differences between watt and kilowatt-hour.
    Answer:
  • Watt is the unit of power; kilowatt-hour is the unit of energy.
  • Watt measures rate of doing work; kilowatt-hour measures amount of energy consumed.
  • 1 kilowatt-hour = 3.6 × 10⁶ joules.

 

  1. A 60 kg man runs at 5 m/s. Find his kinetic energy.
    Answer:
    K.E. = ½ × 60 × 5² = ½ × 60 × 25 = 750 J

 

  1. Why is no work done by a person standing with a load on his head?
    Answer:
    Because displacement is zero, and work = force × displacement, hence work = 0.

 

  1. What happens to the kinetic energy if the velocity is tripled?
    Answer:
    Since K.E. ∝ v², if velocity is tripled, K.E. becomes 9 times.

 

  1. A 1000 W heater is used for 30 minutes. Calculate energy consumed in joules.
    Answer:
    E = P × t = 1000 × (30 × 60) = 1000 × 1800 = 1.8 × 10⁶ J

 

  1. Why is kilowatt-hour used as commercial unit of energy?
    Answer:
    Because joules are too small for practical use, kilowatt-hour provides a convenient large-scale measure for electrical energy consumed.

 

  1. Explain the energy change in a wound-up spring toy.
    Answer:
    The spring stores elastic potential energy which is converted into kinetic energy when the toy moves.

 

  1. Can a body have energy without work being done? Explain with an example.
    Answer:
    Yes, a stationary object at height has potential energy though no work is currently being done. Example: Water in a raised tank.

 

  1. A body of mass 2 kg is moving at 10 m/s. Calculate kinetic energy and interpret the result.
    Answer:
    K.E. = ½ × 2 × 10² = 1 × 100 = 100 J
     Interpretation: 100 J of work was required to bring the object to this velocity.

 

  1. Explain why a falling body gains kinetic energy but loses potential energy.
    Answer:
    As the body falls, height decreases (thus potential energy decreases), but speed increases (so kinetic energy increases). Total energy remains constant.

 

  1. A man pulls a cart with a force of 200 N through 10 m. Find the work done.
    Answer:
    W = F × d = 200 × 10 = 2000 J

 

  1. Define energy and explain its classification.
    Answer:
    Energy is the capacity to do work. It is classified as:
  • Kinetic energy (due to motion)
  • Potential energy (due to position)
     Other forms: Electrical, Thermal, Sound, Chemical, Nuclear.

 

  1. Name three devices that convert mechanical energy into electrical energy.
    Answer:
  1. Generator
  2. Windmill
  3. Hydroelectric turbine

 

  1. A body does 500 J of work in 10 seconds. Calculate its power.
    Answer:
    Power = Work/Time = 500/10 = 50 W

 

  1. Discuss any three renewable sources of energy.
    Answer:
  1. Solar Energy – derived from the sun, available abundantly.
  2. Wind Energy – generated by wind turbines.
  3. Hydroelectric Energy – generated by water stored in dams.

 

  1. Explain why energy transformation is necessary in machines.
    Answer:
    Machines convert one form of energy into another to perform useful work efficiently, e.g., converting electrical energy to mechanical energy in motors.

 

  1. What is gravitational potential energy? How does it depend on height?
    Answer:
    It is the energy possessed by a body due to its height above the ground. It increases linearly with height as P.E. = mgh.

 

  1. Why is work a scalar quantity?
    Answer:
    Because it has magnitude but no direction, and is defined as scalar (dot) product of force and displacement.

 

  1. A 25 kg object is lifted vertically by 4 m. Calculate the work done and its energy form.
    Answer:
    W = mgh = 25 × 9.8 × 4 = 980 J
     This is stored as gravitational potential energy.

Give Reasons

  1. Work done is zero when a person holds a heavy suitcase without moving.
    Answer: Because there is no displacement in the direction of force.

 

  1. No work is done in uniform circular motion.
    Answer: Because the force (centripetal) is perpendicular to displacement at every point.

 

  1. Work done is negative when a body is lifted and then allowed to fall.
    Answer: Because the displacement during fall is in the direction opposite to the applied force (gravity acts downward while lifting was upward).

 

  1. A man pushing a wall does no work.
    Answer: Because there is no displacement of the wall.

 

  1. Kinetic energy is always positive.
    Answer: Because it is proportional to the square of velocity, which is always positive.

 

  1. Potential energy increases with height.
    Answer: Because P.E. = mgh and h is directly proportional to P.E.

 

  1. A stretched bow has potential energy.
    Answer: Because work is done in changing its shape, which gets stored as elastic potential energy.

 

  1. A moving bullet has kinetic energy.
    Answer: Because it possesses energy due to its motion.

 

  1. Energy is said to be conserved.
    Answer: Because it can neither be created nor destroyed, only transformed.

 

  1. Kinetic energy increases rapidly with speed.
    Answer: Because K.E. is directly proportional to the square of velocity.

 

  1. Work done by friction is negative.
    Answer: Because friction acts opposite to the direction of displacement.

 

  1. Power is a scalar quantity.
    Answer: Because it has only magnitude, not direction.

 

  1. Work done in lifting a body is positive.
    Answer: Because the applied force and displacement are in the same direction.

 

  1. Potential energy is zero at ground level.
    Answer: Because height (h) from ground is zero and P.E. = mgh.

 

  1. More power is required to do the same work in less time.
    Answer: Because power is inversely proportional to time.

 

  1. A man running has kinetic energy.
    Answer: Because he is in motion and K.E. depends on speed.

 

  1. A falling object gains kinetic energy.
    Answer: Because its velocity increases due to gravity.

 

  1. Commercial unit of energy is kilowatt-hour.
    Answer: Because joule is too small for measuring large-scale energy usage.

 

  1. A flying airplane possesses both kinetic and potential energy.
    Answer: Because it has speed (K.E.) and is at a height (P.E.).

 

  1. No work is done by gravitational force on a satellite.
    Answer: Because the force is perpendicular to displacement in circular motion.

 

  1. Energy is needed to perform work.
    Answer: Because energy is the capacity to do work.

 

  1. 1 horsepower is not an SI unit.
    Answer: Because it is a traditional unit; the SI unit of power is watt.

 

  1. Light energy can be converted into electrical energy.
    Answer: Because solar cells use photovoltaic effect to convert sunlight into electricity.

 

  1. A compressed spring stores energy.
    Answer: Because work is done in deforming it and is stored as elastic potential energy.

 

  1. A person walking on a level road does no work against gravity.
    Answer: Because there is no vertical displacement.

 

  1. Electric bulbs produce heat along with light.
    Answer: Because electrical energy gets converted into both light and heat.

 

  1. Kinetic energy is directly proportional to mass.
    Answer: Because K.E. = ½ mv², and mass appears in the numerator.

 

  1. Gravitational potential energy increases with mass.
    Answer: Because P.E. = mgh and is directly proportional to mass.

 

  1. A body can possess energy even when not in motion.
    Answer: Because it may have potential energy due to position.

 

  1. Power is a measure of efficiency.
    Answer: Because it tells how fast work is done.

 

  1. Mechanical energy is conserved in absence of friction.
    Answer: Because no energy is lost in overcoming friction.

 

  1. A body at a height has potential energy.
    Answer: Because of its position above the ground.

 

  1. Windmills produce electricity.
    Answer: Because mechanical energy of moving air is converted to electrical energy.

 

  1. Solar panels are used to generate electricity.
    Answer: Because they convert solar energy to electrical energy using photovoltaic cells.

 

  1. Power of an engine is measured in horsepower.
    Answer: Because it’s a conventional unit used for rating engines.

 

  1. Water stored at height is used in hydroelectric power stations.
    Answer: Because it has gravitational potential energy which gets converted to electricity.

 

  1. Mechanical energy is the sum of kinetic and potential energy.
    Answer: Because both contribute to the ability of a body to do work.

 

  1. A falling stone speeds up.
    Answer: Because gravitational force causes acceleration.

 

  1. A lighted torch has chemical energy.
    Answer: Because chemicals in the battery convert to light and heat energy.

 

  1. Kinetic energy becomes zero at the topmost point of projectile.
    Answer: Because the vertical velocity becomes zero at that point.

 

  1. Energy conversion is essential in practical life.
    Answer: Because we often need energy in forms different from the one available.

 

  1. Work done is maximum when force and displacement are parallel.
    Answer: Because the angle between them is zero, making cosθ = 1.

 

  1. Unit of energy and work is the same.
    Answer: Because energy is capacity to do work; both are measured in joules.

 

  1. A fan converts electrical energy into mechanical energy.
    Answer: Because it uses electric current to rotate blades.

 

  1. A pendulum stops eventually.
    Answer: Because of energy loss due to air resistance and friction.

 

  1. Machines are rated in terms of their power.
    Answer: Because it indicates how quickly they can do work.

 

  1. A stretched rubber band can do work.
    Answer: Because it has elastic potential energy.

 

  1. Friction reduces mechanical energy.
    Answer: Because it converts useful mechanical energy to heat.

 

  1. A battery lights a bulb.
    Answer: Because chemical energy converts into electrical energy, then into light.

 

  1. No work is done by a person standing still.
    Answer: Because there is no displacement of the body.

Arrange the Words 

Case Studies

Case Study 1:
 Ravi uses a pulley to lift a bucket of water from a well. He applies a constant force of 100 N and lifts the bucket to a height of 10 meters in 25 seconds.

Q1. Calculate the work done by Ravi.
 Answer: Work = Force × Displacement = 100 × 10 = 1000 J

Q2. Calculate the power used.
 Answer: Power = Work / Time = 1000 / 25 = 40 W

 

Case Study 2:
 A car engine does 60000 J of work in 10 seconds.

Q1. What is the power of the engine?
 Answer: Power = 60000 / 10 = 6000 W

Q2. Convert the power into kilowatts.
 Answer: Power = 6000 / 1000 = 6 kW

 

Case Study 3:
 A student climbs a staircase carrying a 20 kg load to a height of 5 m in 15 seconds.

Q1. Calculate the work done.
 Answer: Work = mgh = 20 × 9.8 × 5 = 980 J

Q2. Find the power developed.
 Answer: Power = 980 / 15 = 65.33 W

 

Case Study 4:
 A machine lifts a 50 kg mass vertically through 8 meters in 10 seconds.

Q1. How much work is done?
 Answer: Work = mgh = 50 × 9.8 × 8 = 3920 J

Q2. Calculate the power.
 Answer: Power = 3920 / 10 = 392 W

 

Case Study 5:
 A boy kicks a football of mass 0.5 kg and gives it a velocity of 20 m/s.

Q1. Find the kinetic energy acquired by the ball.
 Answer: K.E. = ½ mv² = ½ × 0.5 × 20² = 100 J

Q2. What was the work done on the ball?
 Answer: Work = Change in K.E. = 100 J

 

Case Study 6:
 In a hydroelectric dam, water falls from a height of 40 m. Mass of water falling per second is 1000 kg.

Q1. What is the potential energy per second?
 Answer: P.E. = mgh = 1000 × 9.8 × 40 = 392000 J

Q2. What is the power generated (ignoring losses)?
 Answer: Power = 392000 W or 392 kW

 

Case Study 7:
 A body of mass 2 kg is thrown vertically upwards with a velocity of 10 m/s.

Q1. Find its initial kinetic energy.
 Answer: K.E. = ½ × 2 × 10² = 100 J

Q2. What is the maximum height reached?
 Answer: K.E. = P.E. at top → mgh = 100 → h = 100 / (2 × 9.8) = 5.1 m

 

Case Study 8:
 An electric motor consumes 3 kWh of energy in 2 hours.

Q1. What is the power rating of the motor?
 Answer: Power = Energy / Time = 3 kWh / 2 h = 1.5 kW

Q2. Convert this into watts.
 Answer: 1.5 kW = 1500 W

 

Case Study 9:
 A moving vehicle has a mass of 1500 kg and moves at a speed of 20 m/s.

Q1. Calculate its kinetic energy.
 Answer: K.E. = ½ × 1500 × 20² = 300000 J

Q2. What happens to this energy if brakes are applied?
 Answer: It is converted into heat and sound energy.

 

Case Study 10:
 A child throws a stone of mass 0.2 kg vertically upward. It reaches a height of 25 m.

Q1. What is its potential energy at the highest point?
 Answer: P.E. = mgh = 0.2 × 9.8 × 25 = 49 J

Q2. What is the initial kinetic energy?
 Answer: Same as P.E. = 49 J (by conservation of energy)

 

Case Study 11:
 A windmill converts 500 J of kinetic energy into 300 J of electrical energy.

Q1. What is the efficiency of the windmill?
 Answer: Efficiency = (300 / 500) × 100 = 60%

Q2. How much energy is wasted?
 Answer: 500 – 300 = 200 J

 

Case Study 12:
 A pump raises 100 liters of water (mass = 100 kg) to a tank 6 m above the ground.

Q1. Calculate work done.
 Answer: Work = mgh = 100 × 9.8 × 6 = 5880 J

Q2. If pump takes 10 s, find power.
 Answer: Power = 5880 / 10 = 588 W

 

Case Study 13:
 A 200 W electric bulb glows for 5 hours.

Q1. What is the energy consumed in kWh?
 Answer: Energy = Power × Time = 200 × 5 = 1000 Wh = 1 kWh

Q2. Convert to joules.
 Answer: 1 kWh = 3.6 × 10⁶ J

 

Case Study 14:
 A crane lifts a box of 500 kg through a height of 15 meters in 10 seconds.

Q1. Work done = ?
 Answer: Work = 500 × 9.8 × 15 = 73500 J

Q2. Power = ?
 Answer: Power = 73500 / 10 = 7350 W

 

Case Study 15:
 Two students A and B do equal work, but A finishes in less time.

Q1. Who is more powerful and why?
 Answer: Student A, because power = work / time, and time is less for A.

 

Case Study 16:
 A body of 4 kg is moving at 3 m/s.

Q1. What is its kinetic energy?
 Answer: K.E. = ½ × 4 × 9 = 18 J

Q2. What is the work done to bring it to this velocity?
 Answer: Work = K.E. = 18 J

 

Case Study 17:
 Water in a tank is at 20 m height and flows down to spin a turbine.

Q1. What energy conversion takes place?
 Answer: Gravitational Potential Energy → Kinetic Energy → Mechanical → Electrical

Q2. Why is height important?
 Answer: Because P.E. = mgh; greater h gives more energy.

 

Case Study 18:
 A 1000 W microwave runs for 1800 seconds.

Q1. Energy consumed = ?
 Answer: Energy = 1000 × 1800 = 1.8 × 10⁶ J

Q2. Convert to kWh.
 Answer: 1.8 × 10⁶ J = 0.5 kWh

 

Case Study 19:
 A pendulum swings back and forth in vacuum.

Q1. Is mechanical energy conserved?
 Answer: Yes, because there’s no friction or air resistance.

Q2. At which position is P.E. maximum?
 Answer: At the extreme ends

 

Case Study 20:
 A stone falls freely from rest.

Q1. What happens to potential energy during fall?
 Answer: It decreases.

Q2. What happens to kinetic energy?
 Answer: It increases.

Numericals

ICSE Grade 10

3500/-
  • All Subjects
  • Free Study Material
  • MCQ Tests
  • Theory Tests
  • Assignments
Register

Find out free resources that you need.

ICSE

Grade 8

Grade 9

Grade 10

CBSE

Grade 8

Grade 9

Grade 10

Subjects we teach

“Arise, awake, and learn by approaching the excellent teachers”

Shiksha Marg 108 gives you all free resources to ensure you get the best results. Get ready for you ICSE and CBSE exams!.

ENROLL
ENROLL
error:
Scroll to Top