Question

A block of mass m 1 sits at rest on a table over a hole in the table. From below the table, a
bullet of mass m 2 is fired vertically upwards into the block. The bullet imbeds itself in the block.
The block and bullet rise to a maximum height h. What is the bullet’s initial speed? Answer in
terms of m 1, m 2, h, and g.

Answer 1

The law of conservation of linear momementum
m1•v +0=(m1+m2) •u
v=(m1+m2) •u/m1.
The law of conservation of energy
(m1+m2) •u²/2=(m1+m2) •g•h,
u=sqrt(2•g•h).
v=(m1+m2) •u/m1= (m1+m2) •sqrt(2•g•h)/ m1.