Question

In an experiment designed to determine the velocity of a bullet fired by a certain gun, a wooden block of mass M = 555.0 g is supported only by its edges, and a bullet of mass m = 7.25 g is fired vertically upward into the block from close range below. After the bullet embeds itself in the block, the block and the bullet are measured to rise to a maximum height of 40.0 cm above the block's original position. What is the speed of the bullet just before impact?

Answer 1

This problem is based upon conservation of energy, initially there is kinetic energy in the bullet which gets converted into gravitation potential energy completely when block and bullet reach maximum hieght in there flight.

Since there is an inelastic collision between block and the bullet, there will be some loss of energy hence,

Speed of bullet plus block initially is,

=

Now using conservation of momentum we have,

7.25*v = (7.25 + 555)*2.8

v = 217.144 m/s is the speed of bullet just before collision