Question

A 60 g ball of clay is thrown horizontally at 40 m/s toward a 1.5 kg block sitting at rest on a frictionless surface. the clay hits and sticks to the block. part a what is the speed of the block and clay right after the collision?

Answer 1

The solution for this problem is:
Let u denote speed. 

Equating momentum before and after collision: 
= 0.060 * 40 = (1.5 + 0.060) u 
= 2.4 = 1.56 u
= 2.4 / 1.56 = 1.56 u / 1.56
= 1.6 m / s is the answer for this question. This is the speed after the collision.