A 3. kg ball of putty moving at 1 m/s collides and sticks to a 2 kg ball initially at rest. The putty and ball then move with a momentum of
A) 0 N-s.
B) 3 N-s.
C) 4 N-s.
D) 2 N-s.
E) 1 N-s.

Question

Quizplus · Accepted Answer

The total momentum before the collision is the sum of the momentums of the two objects. Since only the 3 kg ball of putty is moving initially, its momentum is its mass times its velocity: $3 \, \text{kg} \times 1 \, \text{m/s} = 3 \, \text{N-s}$. By the law of conservation of momentum, the total momentum after the collision is the same as before, which is 3 N-s.

A 3 Kg Ball of Putty Moving at 1 M/s Collides