A body of mass m moving with velocity v collides head on with another body of mass 2m which is initially at rest. The ratio of K.E of colliding body before and after collision will be

Explanation

Suppose after the collison the block of mass m moes at a velocity `u_1` and the block of mass 2m moves at a velocity `u_2`. By conservationfo momentum,
`mv=mu_1+2mu_2` ……..i
the velocity of seperation is `u_2-u_1` and the velocity of approach is v.
So, `u_2-u_1=v/2`
find i and ii `u_1=0 and u_2=v/2`