Question

Initially a soccerball is going 37.5m/s south. In the end, it it travelling at 2.6m/s south. The balls changing in momentum is 17.24kg m/s North. Find the ball's mass.

Answer 1

The balls changing in momentum is given by

$$\Delta {\bf p}=m({\bf v_f}-{\bf v_i})$$

In projection on the North direction

$$\Delta p=m(v_i-v_f)$$

Hence, the mass of ball

$$m=\frac{\Delta p}{v_i-v_f}=\frac{17.24}{37.5-2.60}=0.5\:\rm kg.$$