A body of mass 10 kg is moving with a velocity 20 m s^-1.

If the mass of the body is doubled and its velocity is halved,

find:

(i) the initial kinetic energy, and

(ii) the final kinetic energy.

A truck weighing 1000 kg changes its speed from 36 km/h to 72 km/h in 2 minutes.

Calculate:

(i) the work done by the engine and

(ii) its power.

(g =10 m/ s^-2)

How much work is needed to be done on a ball of mass 50g to give it a momentum of 5 kg m s^-1?

How much energy is gained by a box of mass 20 kg when a man

(a) carrying the box waits for 5 minutes for a bus?

(b) runs carrying the box with a speed of 3 ms^-1 to catch the bus?

(c) raises the box by 0.5 m in order to place it inside the bus?

(g=10 ms^-2)