question_answer

A bullet of mass 'a', velocity 'b' is fired into a large block of wood of mass 'c' which is at rest. After that, both the block of wood and bullet move with a common velocity 'v', then find velocity.

Answer:

Bullet (B)	Wood (w)
\[{{m}_{B}}=a\]	\[{{m}_{w}}=c\]
\[{{u}_{B}}=b\]	\[{{u}_{w}}=0\]

\[{{V}_{B}}={{V}_{w}}=V=?\] \[\therefore V=\frac{{{m}_{B}}{{u}_{B}}+{{m}_{w}}{{u}_{w}}}{{{m}_{B}}+{{m}_{w}}}=\frac{ab+0}{a+c}=\frac{ab}{a+c}\]