Question

Two identical balls A and B collide head on elastically. If velocities of A and B, before the collision are +0.5m/s and -0.3m/s respectively, then the velocities after the collision, are ___________

(a) -0.5m/s and +0.3m/s

(b) +0.5m/s and +0.3m/s

(c) +0.3m/s and -0.5m/s

(d) -0.3m/s and +0.5m/s

I had been asked this question in an international level competition.

My question is based upon Moment of Inertia topic in chapter System of Particles and Rotational Motion of Engineering Physics I

Answer 1

Right choice is (d) -0.3m/s and +0.5m/s

To explain I would say: In an elastic collision between two bodies of equal masses, velocities get exchanges after collision. vA=-0.3m/s and vB=+0.5m/s.