Question

Consider two identical particles released from rest and moving towards each other under the influence of mutual gravitational force. The velocity of centre of mass of the two particle system:

• A. is zero
• B. is constant$(\ne 0)$
• C. increases as the separation decreases
• D. none of the above

Answer 1

The correct option is A is zero

Since the external force on the two-particle system is zero, the position of the centre of mass remains stationary and so does its velocity. Therefore velocity of the centre of mass is zero.