Question 1

A roller coaster car is raised to a height of 65 m and released from rest.

What is the maximum possible speed of the car?

  A  

11 m s–1

  B  

25 m s–1

  C  

36 m s–1

  D  

130 m s–1

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Question 2

A car exerts a driving force of 500 N when travelling at a constant speed of 72 km h−1 on a level track. What is the work done in 5 minutes?

  A  

3.0 × 106 J

  B  

2.0 × 106 J

  C  

2.0 × 105 J

  D  

1.1 × 105 J

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Question 3

An electric motor of input power 100 W raises a mass of 10 kg vertically at a steady speed of 0.5 m s−1 . What is the efficiency of the system?

  A  

5 %

  B  

12 %

  C  

50 %

  D  

100 %

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Question 4

Which is approximately equal to 3 kW h?

  A  

3 × 103 J

  B  

1 × 104 J

  C  

2 × 105 J

  D  

1 × 107 J

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Question 5

A car of mass 1000 kg accelerates uniformly from rest to a speed of 25.0 m s–1 in 50.0 s.

The car is travelling along a horizontal road.

What is the average useful power output of the car over this period?

  A  

0.50 kW

  B  

2.00 kW

  C  

6.25 kW

  D  

12.5 kW

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Question 6

An electric vehicle is driven by a motor which produces a constant driving force.

The vehicle travels from rest along a straight horizontal road.

Friction and air resistance are negligible.

Which statement describes the variation with time of the power developed by the motor?

  A  

it stays constant

  B  

it increases linearly from zero


  C  

it increases non-linearly from zero

  D  

it increases from zero to a maximum and then decreases


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Question 7

A force of 12 N moves an object at an angle θ to the force. The object travels 9.6m and the work done by the force is 52 J.

What is the angle θ ?

  A  

1.1°


  B  

27°


  C  

63°


  D  

90°


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Question 8

The frictional force acting on an object falling vertically through water is directly proportional to its speed squared.

What is the correct relationship between P, the rate of work done against the frictional force, and the speed v of the object?

  A  

P ∝ v –1

  B  

P ∝ v


  C  

P ∝ v2

  D  

P ∝ v3

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Question 9

A force of 1000 N is needed to lift the hook of a crane at a steady velocity. The crane is then used to lift a load of mass 1000 kg at a velocity of 0.50 m s–1.

How much of the power developed by the motor of the crane is used in lifting the hook and the load? Assume that the acceleration of free fall g is equal to 10 m s–2.

  A  

5.0 kW 

  B  

5.5 kW

  C  

20 kW

  D  

22 kW

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Question 10

A man has a mass of 80 kg. He ties himself to one end of a rope which passes over a single fixed pulley. He pulls on the other end of the rope to lift himself up at an average speed of 50 cm s–1.

What is the average useful power at which he is working?

  A  

40 W

  B  

0.39 kW

  C  

4.0 kW

  D  

39 kW

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