Two balls of masses m and 2m moving in opposite directions collide head on elastically with velocities `v` and `2v`. Find their velocities after collision.

Explanation

Here, `v_(1)=-v, v_(2)=2v, m_(1) = m and m_(2) = 2m`

Substituting these values in Eqs. (iii) and (iv), we get
`v_(1)^(') = ((m-2m)/(m+2m)) (-v) + ((4m)/(m+2m))(2v)`
or `v_(1)^(') = (v/3) + (8v/3) = 3v`
and `v_(2)^(') = ((2m-m)/(m +2m))(2v) + ((2m)/(m+2m))(-v)`
or `v_(2)^(') = (2/3)v - (2/3)v = 0`

i.e., the second particle (of mass 2m) comes to a rest while the first (of mass m) moves with velocity 3v in the direction. shown in figure given above.