Lesson 3.4.1.7

3.4.1.7 Work, energy and power Quiz: AQA Physics, Unit 4

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.4.1.7, Work, energy and power: 20 multiple choice questions for the AQA Physics (7408), Unit 4: Mechanics and materials, written with Revision Ninja.

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The 20 questions

  1. Work done by a constant force F at angle theta to the displacement s is given by:

    • W = F s sin(theta)
    • W = F s / cos(theta)
    • W = F s cos(theta)
    • W = F s tan(theta)

  2. Power is defined as:

    • the energy transferred per unit charge
    • the work done per unit mass
    • the force multiplied by the acceleration
    • the rate of doing work, or rate of energy transfer

  3. Efficiency of a machine is given by:

    • useful output power divided by input power
    • total output power multiplied by input power
    • input power divided by useful output power
    • useful output power minus input power

  4. The area under a force-displacement graph represents:

    • the power delivered by the force
    • the impulse of the force
    • the work done by the force
    • the momentum transferred by the force

  5. Which unit is equivalent to the watt?

    • J s^-1
    • N m^-1
    • J s
    • kg m s^-1

  6. When a force acts perpendicular to the displacement, the work done by that force is:

    • equal to force times displacement
    • equal to force divided by displacement
    • zero
    • at its maximum possible value

  7. Which expression gives power for a force acting along the direction of velocity?

    • P = F / v
    • P = F v^2
    • P = F v
    • P = F^2 v

  8. A 2.0 kg object is raised vertically through 3.0 m at constant speed (g = 9.8 m/s^2). How much work is done against gravity?

    • 58.8 J
    • 117.6 J
    • 19.6 J
    • 6.0 J

  9. A motor with input power 100 W raises a 4.0 kg mass at a steady 1.0 m/s (g = 9.8 m/s^2). What is its efficiency?

    • about 98%
    • about 25%
    • about 39%
    • about 61%

  10. A car engine delivers 30 kW of output power at a steady speed of 20 m/s. What is the driving force?

    • 150 N
    • 600 N
    • 1500 N
    • 6000 N

  11. A 25 N force acts at 30 degrees above the horizontal to push a crate 10 m horizontally. What is the work done by the force?

    • about 433 J
    • about 217 J
    • about 125 J
    • 250 J

  12. A 1500 W heater runs for 4 minutes. What energy does it transfer?

    • 90 kJ
    • 6.25 kJ
    • 360 kJ
    • 3.6 MJ

  13. A force increases uniformly from 0 to 40 N as an object moves 5.0 m in the direction of the force. What is the work done?

    • 100 J
    • 20 J
    • 40 J
    • 200 J

  14. A lift motor draws 2.4 kW and delivers useful output of 1.8 kW. What is its efficiency?

    • 75%
    • 60%
    • 133%
    • 25%

  15. A 1200 kg car increases its speed from 10 m/s to 20 m/s. Assuming no resistive forces, what work does the engine do?

    • 360 kJ
    • 180 kJ
    • 120 kJ
    • 300 kJ

  16. A pump raises 500 kg of water per minute through 10 m. Ignoring losses, what is the average power required?

    • about 49 kW
    • about 8.2 kW
    • about 820 W
    • about 82 W

  17. A 1000 kg car starts from rest with constant engine power 20 kW, ignoring resistive forces. How long does it take to reach 20 m/s?

    • 10 s
    • 20 s
    • 40 s
    • 5 s

  18. A variable force F = 4x newtons acts along x from x = 0 to x = 3.0 m. What is the work done?

    • 9 J
    • 18 J
    • 36 J
    • 12 J

  19. A machine has input power 500 W and output power 350 W. How much energy is wasted in 10 s?

    • 5000 J
    • 1500 J
    • 3500 J
    • 350 J

  20. A student calculates a motor efficiency of 110%. Which response best evaluates this result?

    • The result is correct because useful output can exceed input when the load falls.
    • The motor has drawn energy from its surroundings, so the efficiency value is valid.
    • It is a measurement error, since efficiency cannot exceed 100% and the input power, height or time was wrongly measured.
    • Efficiency can exceed 100% for motors that run hot, so the result is valid.

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