Question

Two particles A and B, of mass m each, are joined by a rigid mass less rod of length l. A particle P of mass m, moving with a speed u normal to AB, strikes A and sticks to it. The centre of mass of the ‘A + B + P’ system is C.

(a) The velocity of C before impact is u/3.

(b) The velocity of C after impact is u/3.

(c) The velocity of ‘A + P’ immediately after impact is u/2.

(d) The velocity of B immediately after impact is zero.

Answer 1

Correct Answer is: (a, b, c, & d)

As all three particles are part of the system, any impact between them produces no change in the velocity of their centre of mass. Also, ‘A + B’ can exert a force on B only along the rod, i.e., normal to u.