FRICTION AND BRAKING
3 marks · NormalThe table below shows the stopping distances for a car with good tyres and brakes on a dry road:
| Speed (mph) | Thinking distance (m) | Braking distance (m) | Total stopping distance (m) |
|---|---|---|---|
| 30 | 9 | 14 | |
| 50 | 15 | 38 |
(a) Complete the table by calculating the total stopping distance for each speed.
(b) Use the table to state how the total stopping distance changes as the speed increases.
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.
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(a) 30 mph: 9 m + 14 m = 23 m; 50 mph: 15 m + 38 m = 53 m
(b) The total stopping distance increases as the speed increases.
Common mistakes: Adding only one value.; Stating 'it increases' without reference to the data.
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Correct addition for the first row: 9 + 14 = 23 m.
M1 (a) · 1 mark · Correct addition for the second row: 15 + 38 = 53 m.
B1 (b) · 1 mark · States from the table that stopping distance increases as speed increases.
Worked solution
(a) For 30 mph: 9 m + 14 m = 23 m. For 50 mph: 15 m + 38 m = 53 m.
(b) As speed increases from 30 mph to 50 mph, the total stopping distance increases from 23 m to 53 m.