# GCSE Questions: Forces

Q31. Speed limits on roads increase safety.

The braking distance of a car increases as the speed of the car increases.

(a) Give two other factors that increase the braking distance of a car.

[2 marks]

(b) Explain why the driver's reaction time affects the thinking distance of a car.

[2 marks]

(c) Scientists have investigated how drinking alcohol affects a personâ€™s reaction time.

The graph shows the results of the investigation.

Which of the following conclusions can be made from the graph?

Tick two boxes:

 Every person's reaction time increases after drinking alcohol. Mean reaction time increases after drinking alcohol. Some people's reaction time is not affected by drinking alcohol. The change in reaction time is not the same for all people after drinking alcohol. There is a smaller range of reaction times after drinking alcohol.

[2 marks]

(d) The diagram shows some speed cameras on a road.

The speed cameras determine the average speed of cars on the road.

The speed limit on the road shown below is 20 m/s. The cameras in are 1.5 km apart.

(i) Calculate the minimum time it takes to travel 1.5 km without breaking the speed limit.

[4 marks]

(ii) Explain why the average speed of a car between the cameras and the average velocity of the car between the cameras are different.

[3 marks]

[13 Marks TOTAL]