Question

A car weighing 1000kg and travelling at 30m/s stop at the distance of 50m decelerating uniformly. What is tge force exerted on it by the break. What is work done by the breaks

Answer 1

Initial velocity (u) = 30 m/s

Final velocity (v) = 0 m/s

Distance covered before coming to rest (s) = 50 m

Let the acceleration be a.

$v^2 = u^2 + 2as$

$a = - \frac{30^2}{100}$

a = - 9 m/s^2

Force exerted by the brake = m × a

Force = - 1000 × 9

a) Force = - 9000 N

b) Work done = Force × displacement

Work done = - 9000 × 50

Work done = - 45000 Joules

Hence, the work done by the brakes = - 45000 Joules