Two particles of equal masses moving with same collide perfectly inelastically. After the collision the combined mass moves with half of the speed of the individual masses. The angle between the initial momenta of individual particle is

Options

A. `30^(@)`
B. `6^(@)`
C. `120^(@)`
D. None of these

Answer

C

Explanation

Net linear mometum before and after the collision must remain same .
`sqrt((mv)^(2)+(mv)^(2)+2(mv)(mv)cos theta ) = 2m (v/2)`
In above relation `theta ` is angle between initial linear momenta of particles .
`rArr (mv)^(2)+(mv)^(2) +2(mv)(mv)cos theta = (mv)^(2)`
`rArr " " cos theta = - 1/2 rArr theta = 120^(@)`