A bullet of mass `m` hits a target of mass M hanging by a string and gets embeded in it. If the block rises to a height h as a result of this collision, the velocity of the bullet before collision is

Explanation

Let `v_(1)` be velocity of the system of block and the bullet. Applying principle of conservation of linear momentum, `(m+M) v_(1)=mv`
`v_(1)=(mv)/((m+M))` …(i)
As K.E. of the system
`=` P.E. of the system at height h
`v_(1)=sqrt(2gh)`
From (i), `v=((m+M)v_(1))/(m)=((m+M)sqrt(2gh))/(m)`