Question

State if each of the following statements is true or false. Give reasons for your answer.

(a) In an elastic collision of two bodies, the momentum and energy of each body is conserved.

(b) Total energy of a system is always conserved, no matter what internal and external forces on the body are present.

(c) Work done in the motion of a body over a closed loop is zero for every force in nature.

(d) In an inelastic collision, the final kinetic energy is always less than the initial kinetic energy of the system.

Answer 1

(a) False. In an elastic collision of two bodies, the momentum and energy of the system is conserved.

(b) False. Some energy is lost in heat, so it is not conserved.

(c) False. It is true only for conservative forces. For non-conservative forces, work done over one cycle is not zero.

(d) True. Some energy is lost in internal friction and heat.