FRICTION AND BRAKING
3 marks · NormalA cyclist is riding at 20 mph on a dry road. The thinking distance for the cyclist is 6 m. The braking distance is also 6 m. The road suddenly becomes wet.
Calculate the total stopping distance for the cyclist on the dry road.
Explain what will happen to the stopping distance if the road becomes wet. State the reason.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) 12 m
(b) The stopping distance will increase because the wet road reduces friction between the tyres and the road, so the braking distance becomes longer.
Show mark scheme and worked solution
Marking points
A1 (a) · 1 mark · Correctly adds 6 m + 6 m to get 12 m.
B1 (b) · 2 marks · Correctly states stopping distance increases on a wet road and explains it's due to decreased friction, increasing braking distance.
Worked solution
(a) Stopping distance on dry road: 6 m + 6 m = 12 m.
(b) On a wet road, stopping distance increases because the braking distance gets longer as there is less friction between the tyres and the road.