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GCSE Questions: Momentum

Q3. (a) A car driver sees the traffic in front is not moving and brakes to stop his car.

The stopping distance of a car is the thinking distance plus the braking distance.

(i) What is meant by the 'braking distance'?

[1 mark]

(ii) The braking distance of a car depends on the speed of the car and the braking force. State one other factor that affects braking distance.

[1 mark]

(iii) How does the braking force needed to stop a car in a particular distance depend on the speed of the car?

[1 mark]

(b) The graph below shows the distance–time graph for the car in the 10 seconds before the driver applied the brakes.

Use the graph to calculate the maximum speed the car was travelling at.

Show clearly how you work out your answer.

[3 marks]

(c) The car did not stop in time. It collided with the stationary car in front, joining the two cars together.

The diagram shows both cars, just before and just after the collision.

(i) The momentum of the two cars was conserved. What is meant by the statement 'momentum is conserved'?

[1 mark]

(ii) Calculate the velocity of the two joined cars immediately after the collision.

[3 marks]

(d) Since 1965, all cars manufactured for use in the UK must have seat belts.

It is safer for a car driver to be wearing a seat belt, compared with not wearing a seat belt, if the car is involved in a collision.

Explain why.

[4 marks]

[14 Marks TOTAL]