Statement 1: Two spheres undergo a perfectly elastic collision. The kinetic energy of system of both spheres is always constant. [There is no external force on system of both spheres].
Statement 2: If net external force on a system is zero, the velocity of centre of mass remains constant.

Options

A. Statement `-1` is True, Statement `-2` is True, Statement`-2` is a correct explanation for Statement`-1`
B. Statement `-1` is True,Statement`-2` is True, Statement`-2` is NOT a correct explanation for Statement`-1`
C. Statement `-1` is True, Statement `-2` is False
D. Statement `-1` is False, Statement `-2` is True.

Answer

D

Explanation

During collision `KE` of system is not constant , hence statement `-1 ` is false.