A block having mass m collides with another stationary block having mass 2m. The lighter block comes to rest after collision. If the initial velocity of the first block is v, then the value of the coefficient of restitution will be?

Correct option is A. 0.5
By conservation of linear momentum
mv = 2mv'
v' = v/2
The value of coefficient of restitution is
e = (Velocity of separation) / (Velocity of approach)
e = (v/2 - 0) / (v - 0)
e = 1/2
e = 0.5
So, The value of coefficient of restitution is 0.5
Hence, A is the correct option