Calculate the amount of work required to stop a car of 1000 kg moving with a speed of 72 km h”1?

Question: Calculate the amount of work required to stop a car of 1000 kg moving with a speed of 72 km h”1?

Initial speed  =72 km/h = 72×5÷18

​ =20 m/sec.

final velocity   v=0

mass   m=1000 kilograms

Work done to stop it   

W=K.E i - K.E f

​W=1/2mu2 -1/2 mv2

​W=1/2 ×1000 (20)2 -0

W=2× 10 5 J