Question

1. if the momentum of object b decreases by 5 kg × m/s after a collision, what happens to the momentum of object a?

it increases by 5 kg × m/s.
it decreases by 10 kg × m/s.
it increases by 10 kg × m/s.
it decreases by 5 kg × m/s.

Explanation:

Step1: Apply the law of conservation of momentum

The law of conservation of momentum states that the total momentum of a closed system remains constant. If object B's momentum decreases by \(5\space kg\cdot m/s\), object A's momentum must change to keep the total momentum the same.

Step2: Determine the change in object A's momentum

Since the total momentum is conserved (\(\Delta p_{total}=0\)), if \(\Delta p_B=- 5\space kg\cdot m/s\), then \(\Delta p_A=-\Delta p_B\). So \(\Delta p_A = 5\space kg\cdot m/s\) (increase).

Answer:

It increases by \(5\space kg\times m/s\).