1. a net force of 100 newton’s is applied to a wagon for 5 seconds. this causes the wagon to undergo a change in momentum of

+/- 500 kg m/s

Explanation:

Change in momentum is due to change in velocity:

(v1 denotes velocity before and v2 velocity after). The change in velocity is cause by the acceleration "a" due to the force applied. We are not told which direction the force acts: is against the current movement (deceleration), or in same direction as the movement of the wagon (acceleration). So I will keep both options open by using +/- in the calculation. The v2 can after appliying the acceleration for a time "t" is written as:

and so the change in momentum is:

The absolute change in momentum is 500 N m/s. The change can be an increase or decrease - we can't tell from the problem statement alone.