A man of mass 50 kg climbs up a ladder of height 15m.

Calculate:

(i) the work done by the man,

(ii) the increase in his potential energy.

(g = 9.8 m s^-2).

A block A, whose weight is 100N, is pulled up a slope of length 5m by means of a constant force F (=100N) as illustrated.

(a) What is the work done by the force F in moving the block A, 5m along the slope?

(b) What is the increase in potential energy of the block A?

(c) Account for the difference in the work done by the force and the increase in potential energy of the block.

If the speed of a car is halved, how does its kinetic energy change?

Two bodies of equal masses are moving with uniform velocities v and 2v. Find the ratio of their kinetic energies.