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)

A body of mass 60 kg has the momentum of 3000 kgms^-1.

Calculate:

(i) the kinetic energy and

(ii) the speed of the body.

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)

A bullet of mass 50g is moving with a velocity of 500ms^-1. It penetrates 10 cm into a still target and comes to rest.

Calculate:

(a) the kinetic energy possessed by the bullet, and

(b) the average retarding force offered by the target.