2.6.2 Gravitational potential energy and conservation of energy Quiz: Pearson Edexcel Physics, Unit 2

The 20 questions

1. The change in gravitational potential energy of a mass m raised through height h near Earth's surface is:

   • (1/2) m g delta h
   • m g delta h
   • m v delta h
   • m g h^2

2. The principle of conservation of energy states that:

   • Energy is always lost to heat in every process.
   • Energy can be created when a force does positive work.
   • Kinetic energy must always equal potential energy.
   • Energy cannot be created or destroyed, so the total energy of an isolated system is constant.

3. A 2.0 kg object is raised through 5.0 m. What is its gain in gravitational potential energy, taking g = 9.8 m s^-2?

   • 49 J
   • 10 J
   • 196 J
   • 98 J

4. A 0.50 kg ball is dropped from 10 m and air resistance is ignored. What is its speed just before it hits the ground, taking g = 9.8 m s^-2?

   • 7.0 m s^-1
   • 14 m s^-1
   • 196 m s^-1
   • 9.8 m s^-1

5. A 500 kg roller coaster starts from rest and descends 20 m without friction. What is its speed at the bottom, taking g = 9.8 m s^-2?

   • 20 m s^-1
   • 196 m s^-1
   • 9.8 m s^-1
   • 40 m s^-1

6. A 0.20 kg ball is dropped from 5.0 m and reaches a speed of 8.0 m s^-1 just before hitting the ground. How much energy is lost to air resistance, taking g = 9.8 m s^-2?

   • 16.2 J
   • 3.4 J
   • 6.4 J
   • 9.8 J

7. A 1.0 kg ball is thrown vertically upwards at 10 m s^-1 from the ground. How high does it rise, taking g = 9.8 m s^-2 and ignoring air resistance?

   • 5.1 m
   • 50 m
   • 1.0 m
   • 10 m

8. A pendulum bob is released from rest at a height of 0.20 m above its lowest point. What is its speed at the lowest point, taking g = 9.8 m s^-2?

   • 4.0 m s^-1
   • 0.20 m s^-1
   • 0.98 m s^-1
   • 2.0 m s^-1

9. For a projectile moving freely with no air resistance, which statement about energy is correct?

   • Total energy decreases steadily as the projectile rises.
   • Potential energy is always zero during flight.
   • Kinetic energy stays constant while potential energy changes.
   • Total energy stays constant as kinetic and gravitational potential energy interchange.

10. A 60 kg skier descends a slope with a vertical drop of 10 m, starting from rest. A friction force of 40 N acts over a slope length of 30 m. What is the speed at the bottom, taking g = 9.8 m s^-2?

    • 20 m s^-1
    • 12.5 m s^-1
    • 14 m s^-1
    • 9.8 m s^-1

11. A solid ball rolls down a slope from rest. Why is its speed at the bottom less than sqrt(2gh) predicted by energy conservation for sliding without rotation?

    • The normal force does negative work on the ball.
    • Some of the energy goes into rotational kinetic energy of the ball.
    • The ball's mass decreases as it rolls.
    • Gravity is weaker on slopes than on level ground.

12. A body falls from rest through a height h with no air resistance. Which statement about its speed is correct?

    • Its speed depends on the height fallen and on g, not on its mass.
    • Its speed depends on its mass and on g.
    • Its speed depends on its mass but not on h.
    • Its speed is independent of g.

13. A 2.0 kg object slides down a frictionless curved track from a height of 3.0 m. What is its kinetic energy at the bottom, taking g = 9.8 m s^-2?

    • 29 J
    • 6.0 J
    • 98 J
    • 59 J

14. A pendulum of length 1.0 m is released from rest at an angle that raises the bob by 0.10 m. What is the bob's speed at the lowest point, taking g = 9.8 m s^-2?

    • 0.10 m s^-1
    • 2.0 m s^-1
    • 1.4 m s^-1
    • 0.98 m s^-1

15. A 3.0 kg object is raised 4.0 m at constant speed. What is the change in its gravitational potential energy?

    • 30 J
    • 118 J
    • 235 J
    • 12 J

16. In a real system, why is the final kinetic energy of a falling object less than the loss of gravitational potential energy?

    • Gravitational potential energy is never converted to kinetic energy.
    • The object's mass increases as it falls.
    • Some energy is transferred to thermal energy of the air and the object by drag.
    • Gravity does negative work on the object as it falls.

17. A 0.40 kg ball rises 1.5 m after being hit upwards. What is its gain in gravitational potential energy, taking g = 9.8 m s^-2?

    • 5.9 J
    • 0.6 J
    • 2.6 J
    • 15 J

18. A 0.50 kg ball starts from rest at the top of a frictionless ramp 8.0 m high. What is its speed at the bottom, taking g = 9.8 m s^-2?

    • 25 m s^-1
    • 4.0 m s^-1
    • 12.5 m s^-1
    • 9.8 m s^-1

19. A 1.5 kg object is lowered by 6.0 m. What is the change in its gravitational potential energy, taking g = 9.8 m s^-2?

    • 88 J
    • 147 J
    • 9.8 J
    • 44 J

20. A 0.30 kg ball is thrown upwards and rises 4.0 m with no air resistance. What was its kinetic energy at launch, taking g = 9.8 m s^-2?

    • 12 J
    • 6.0 J
    • 24 J
    • 1.2 J

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