A truck of mass 1000 kg increases its speed from 36 km h^-1 to 72 km h^-1. Find the increase in its kinetic energy.

A car is moving with a speed of 15 km h^-1 and another identical car is moving with a speed of 30 km h^-1. Compare their kinetic energy.

A pump raises water by spending 4 x 10⁵ J of energy in 10 s. Find the power of pump.

It takes 20 s for a girl A to climb up the stairs while girl B takes 15 s for the same job. Compare:

(a) The work done and

(b) The power spent by them.