Question
A bullet of mass m is fired with velocity u into a block of mass M at rest. What is the final velocity of system supposing bullet remain embedded into the block?
Solution
Initial momentum of block = M x 0 = 0
Initial momentum of bullet = mu
Therefore,
Initial momentum of system (bullet + block)
before the bullet is embedded into block = mu
Let V be the velocity of system (bullet + block)
after bullet gets embedded into block.
∴ Final momentum of system (bullet + block)
after bullet gets embedded into block = (m + M)V
According to law of conservation of momentum,
(m+M)V = mu
This is the final velocity of the system.
