A car of mass is travelling on a straight

PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

A car of mass

1200\,\text{kg}

is travelling on a straight, level road at a speed of

25\,\text{m s}^{-1}

when the driver applies the brakes. The brakes provide a uniform retarding force of

4500\,\text{N}

on the car. (a) Derive an expression for the stopping distance

s

of the car in terms of its mass

m

, its initial speed

v_0

and the magnitude of the retarding force

F

. (b) Hence calculate the numerical value of

s

for the data given above. Take

g = 9.8\,\text{m s}^{-2}

. (c) Determine the time taken for the car to come to rest after the brakes are applied.