Question

Two particles of masses m1 and m2 in projectile motion have velocities v1 and v2 resp. at time t=0. They collide at t=t1. There velocities become v''1 and v''2 at time 2t1 while still moving in air. The value of (m1v''1+m2v''2)-(m1v1+m2v2) is

Answer 1

Linear momentum is conserved. So, if you subtract the initial momentum from the final momentum, what should you get?

Answer 2

if momentum is conserved then we get velocity just after collision and not after time t1 read the question carefully if we v1'and v2' were the speed just after collision then answer would have been zero but its not so.

Answer 3

Don't worry about what happens during the time the objects are interacting between t1 and 2t1.