Lesson 3.11

3.11 Engineering physics: rotational dynamics and thermodynamics Quiz: AQA Physics, Unit 11

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.11, Engineering physics: rotational dynamics and thermodynamics: 20 multiple choice questions for the AQA Physics (7408), Unit 11: Engineering physics (A-level option), written with Revision Ninja.

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The 20 questions

  1. What is the moment of inertia of a point mass m at distance r from the axis of rotation?

    • I = m r
    • I = m r^2 / 2
    • I = m v^2
    • I = m r^2

  2. Which expression gives the rotational kinetic energy of a body with moment of inertia I and angular speed omega?

    • E_k = I omega
    • E_k = I omega^2
    • E_k = (1/2) I omega^2
    • E_k = (1/2) I^2 omega

  3. What is the expression for torque in terms of moment of inertia and angular acceleration?

    • T = I / alpha
    • T = alpha / I
    • T = I omega
    • T = I alpha

  4. What happens to the angular momentum of a body with no external torque acting on it?

    • it stays constant
    • its moment of inertia always stays constant
    • its angular velocity always stays constant
    • its kinetic energy stays constant whatever the torque

  5. A flywheel with moment of inertia 0.5 kg m^2 rotates at 100 rad/s. What is its rotational kinetic energy?

    • 250 J
    • 5000 J
    • 50 J
    • 2500 J

  6. A wheel starts from rest and has a constant angular acceleration of 2.0 rad/s^2 for 5.0 s. What is its angular velocity?

    • 20 rad/s
    • 2.5 rad/s
    • 10 rad/s
    • 5 rad/s

  7. The same wheel accelerates from rest at 2.0 rad/s^2 for 5.0 s. Through what angle has it turned?

    • 10 rad
    • 50 rad
    • 12.5 rad
    • 25 rad

  8. A force of 20 N acts tangentially at a radius of 0.30 m. What torque does it produce?

    • 0.015 N m
    • 66.7 N m
    • 6.0 N m
    • 60 N m

  9. A torque of 6.0 N m turns a shaft through one complete revolution. What work is done?

    • 38 J
    • 6 J
    • 12 J
    • 3.0 J

  10. A constant torque of 6.0 N m acts on a rotor turning at 10 rad/s. What is the power delivered?

    • 60 W
    • 600 W
    • 6 W
    • 0.6 W

  11. A constant torque of 2.0 N m acts for 0.50 s on a wheel of moment of inertia 0.10 kg m^2 that starts at rest. What is its final angular velocity?

    • 1 rad/s
    • 5 rad/s
    • 20 rad/s
    • 10 rad/s

  12. A gas absorbs 500 J of heat and does 200 J of work on its surroundings. What is the increase in its internal energy?

    • 300 J
    • 700 J
    • -300 J
    • 200 J

  13. A gas is held at constant pressure of 2.0 x 10^5 Pa while its volume increases by 0.50 x 10^-3 m^3. What work is done by the gas?

    • 0.1 J
    • 400 J
    • 1000 J
    • 100 J

  14. In an isothermal expansion of an ideal gas, which statement is correct?

    • the work done by the gas is zero
    • the internal energy increases by the work done
    • the heat taken in equals the work done by the gas, since delta U is zero
    • no heat is transferred, since the temperature is constant

  15. A gas is compressed adiabatically. What happens to its temperature?

    • it rises, since work is done on the gas and no heat leaves
    • it remains constant, since no heat is transferred
    • it rises only if heat is added during the compression
    • it falls, since compression always cools a gas

  16. An engine has an input power of 10 kW and a brake power of 3 kW. What is its overall efficiency?

    • 70%
    • 3.3%
    • 30%
    • 300%

  17. A heat engine operates between reservoirs at 500 K and 300 K. What is its maximum theoretical efficiency?

    • 100%
    • 40%
    • 60%
    • 67%

  18. A heat pump operates between a hot reservoir at 300 K and a cold reservoir at 270 K. What is its maximum coefficient of performance?

    • 1.1
    • 10
    • 9
    • 0.90

  19. A heat engine takes in 2000 J from the hot reservoir and rejects 1500 J to the cold reservoir. What is its efficiency?

    • 75%
    • 25%
    • 33%
    • 50%

  20. A four-stroke engine has indicated power 40 kW and brake power 34 kW. What is its mechanical efficiency?

    • 15%
    • 118%
    • 85%
    • 6%

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