A bullet of mass m moving with velocity u passes through a wooden block of mass M=nm. The block is resting on a smooth horizontal floor. After passing through the block the velocity of bullet is v. Its velocity relative to block is

Explanation

`m u =mv + mn v ^(-1) (or) v ^(1) = ((u -v)/( n)) therefore` velocity of bullet relative to block will be
`v _(r) = v - v ^(i) = v - ((u-v)/( n)) = ((1+n)v -u)/( n )`