A car weighing 1200 kg is uniformly accelerated from rest and covers a distace of 40m in 5 sec. calculate the work done by car engine
The work done on a body is always the change in its kinetic energy (final - initial).
Now, as the car was at rest then the initial kinetic energy is zero, so the work done will be
W = KE = (1/2)mv2
here m = 1200 kg
and v = distance/time
= 40/5 = 8 m/s
W = (1/2) X 1200 X (8)2 = 38400 J