Class 9 Physics MCQs: Work And Energy

MCQs (sample)

Showing 25 questions from this chapter. For a full timed test, use “Start online test”.

1. 1. What is the definition of power in physics?

   • The time rate at which work is done
   • The total amount of work done
   • The energy consumed per second
   • The force exerted over a distance
   Answer & explanation

   Correct: The time rate at which work is done

   Power is defined as the time rate at which work is done.

2. 2. What does work mean in a scientific context?

   • When force is applied and distance is covered
   • Simply doing anything
   • Lifting weights only
   • Resting without movement
   Answer & explanation

   Correct: When force is applied and distance is covered

   In science, work specifically means when force is applied and some distance is covered.

3. 3. What is the definition of energy?

   • The capacity of a body to do work
   • The force applied to move an object
   • The weight of an object
   • The speed of an object
   Answer & explanation

   Correct: The capacity of a body to do work

   Energy is defined as 'the capacity of a body to do work'.

4. 4. What is a non-renewable energy resource?

   • An energy resource that cannot be replaced naturally in a short time
   • An energy resource that is replaced rapidly by natural processes
   • An energy resource that comes from the sun
   • An energy resource created from wind power
   Answer & explanation

   Correct: An energy resource that cannot be replaced naturally in a short time

   Non-renewable energy resources are limited and cannot be replaced naturally in a short time.

5. 5. What is the SI unit of power?

   • Joule
   • Watt
   • Horsepower
   • Kilowatt
   Answer & explanation

   Correct: Watt

   The SI unit of power is the watt (W).

6. 6. What is required for work to be done?

   • Force moving an object
   • Time spent
   • Energy without motion
   • Resting position
   Answer & explanation

   Correct: Force moving an object

   Work is done only when an effort or force moves an object.

7. 7. How many forms of energy are mentioned in the content?

   • Five
   • Four
   • Three
   • Six
   Answer & explanation

   Correct: Five

   The content lists five different forms of energy: Chemical, Electrical, Radiant, Sonic, and Nuclear energy.

8. 8. Which of the following energy resources is classified as renewable?

   • Coal
   • Natural gas
   • Wind
   • Petroleum
   Answer & explanation

   Correct: Wind

   Wind is renewable as it is constantly replenished by natural processes.

9. 9. How is one watt defined?

   • 1 joule per 1 second
   • 1 joule per 1 hour
   • 1 joule per 1 minute
   • 1 foot pound per 1 second
   Answer & explanation

   Correct: 1 joule per 1 second

   One watt is defined as 1 joule per 1 second.

10. 10. How is work mathematically defined?

    • Force x Distance
    • Distance x Time
    • Force x Time
    • Speed x Time
    Answer & explanation

    Correct: Force x Distance

    Work done is calculated using the formula W = F x d.

11. 11. What two types can all forms of energy be classified into?

    • Potential and Kinetic Energy
    • Chemical and Radiant Energy
    • Gravitational and Sonic Energy
    • Energy and Work
    Answer & explanation

    Correct: Potential and Kinetic Energy

    All forms of energy can be classified as potential energy (stored) or kinetic energy (due to motion).

12. 12. What process is used to obtain chemical energy from fossil fuels?

    • Photosynthesis
    • Nuclear fission
    • Combustion
    • Refining
    Answer & explanation

    Correct: Combustion

    The chemical energy stored in fossil fuels is obtained through combustion.

13. 13. How many watts are in one horsepower?

    • 550 W
    • 746 W
    • 1000 W
    • 1500 W
    Answer & explanation

    Correct: 746 W

    One horsepower (hp) is defined as 746 W.

14. 14. What type of quantity is work?

    • Scalar quantity
    • Vector quantity
    • Complex quantity
    • Dimensionless quantity
    Answer & explanation

    Correct: Scalar quantity

    Work is classified as a scalar quantity.

15. 15. What is the unit of energy?

    • Newton
    • Joule
    • Watt
    • Pascal
    Answer & explanation

    Correct: Joule

    The unit of energy is joule, abbreviated as J, which is the same as that of work.

16. 16. What is the primary component of natural gas?

    • Coal
    • Methane
    • Uranium
    • Oil
    Answer & explanation

    Correct: Methane

    Natural gas primarily comprises methane.

17. 17. What does one kilowatt hour (kWh) represent?

    • Energy converted in 1 hour at 1 kW
    • Energy used in 1 minute at 1 kW
    • Energy converted in 1 hour at 1000 J
    • Energy required for 1 joule per second
    Answer & explanation

    Correct: Energy converted in 1 hour at 1 kW

    One kWh is the energy converted or consumed in 1 hour at the constant rate of 1 kW.

18. 18. What unit is used to measure work in the SI system?

    • Joules
    • Newtons
    • Meters
    • Watts
    Answer & explanation

    Correct: Joules

    In the International System of Units (SI), work is measured in joules (J).

19. 19. What does the formula Ek = 1/2 mv^2 represent?

    • Potential energy
    • Kinetic energy
    • Total energy
    • Work done
    Answer & explanation

    Correct: Kinetic energy

    The formula Ek = 1/2 mv^2 represents the kinetic energy of a body due to its motion.

20. 20. How is electricity generated from hydroelectric resources?

    • Using fossil fuels
    • Using geothermal energy
    • Using gravitational potential energy of water
    • Using solar radiation
    Answer & explanation

    Correct: Using gravitational potential energy of water

    Hydroelectric generation uses the gravitational potential energy of water to generate electric energy.

21. 21. What does the efficiency 'n' of a machine represent?

    • The ratio of total output to total input
    • The ratio of useful work output to the total work input
    • The amount of energy lost in conversion
    • The total energy consumed over time
    Answer & explanation

    Correct: The ratio of useful work output to the total work input

    Efficiency 'n' is the ratio of useful work output 'Wo' to the total work input 'Wi'.

22. 22. What does one joule represent?

    • Work done by a one-newton force acting over one meter
    • Work done by a ten-newton force acting over ten meters
    • Force applied over any distance
    • Energy consumed in one second
    Answer & explanation

    Correct: Work done by a one-newton force acting over one meter

    One joule is equal to the work done by a one-newton force acting over a one-meter distance.

23. 23. According to the content, how is gravitational potential energy calculated?

    • Ep,grav = mgh
    • Ep,grav = 1/2 mv^2
    • Ep,grav = m + g + h
    • Ep,grav = mhg
    Answer & explanation

    Correct: Ep,grav = mgh

    Gravitational potential energy is given by the formula Ep,grav = mg h.

24. 24. What type of fuel is biomass?

    • Non-renewable fuel
    • Fossil fuel
    • Renewable fuel
    • Nuclear fuel
    Answer & explanation

    Correct: Renewable fuel

    Biomass is considered renewable as it derives energy from ongoing natural processes.

25. 25. Efficiency has what type of unit?

    • Joules
    • Watts
    • No unit
    • Percent
    Answer & explanation

    Correct: No unit

    Efficiency has no unit as it is a ratio of the same quantities.