A bullet of mass 3.9 g was fired at a stationary ball of lead. The head on impact moved the 10 kg ball at a velocity of .3703 m/s. If energy losses due to heat and internal energy are ignored. What was the speed of the bullet?

Answer 1

If the bullet penetrated the lead and stayed there, then to conserve momentum,

.0039v = (10.0039)(.3703)