Question

In an elastic collision of two billiard balls, the total kinetic energy is conserved during the short time of oscillation of the balls (i.e. when they are in contact). Energy spent against friction does not follow the law of conservation of energy.

• A. If both the assertion and reason are true and reason is a correct explanation of the assertion
• B. If both assertion and reason are true but assertion is not a correct explanation of the assertion
• C. If the assertion is true but the reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (D)

If both assertion and reason are false

Answer 2

The billiard balls in an elastic collision are in a deformed state. And their total energy is in the form of $P.E$. and $K.E$. Thus $K.E$. is less than the total energy. The energy spent against friction is dissipated in the form of heat which is not available for doing work.