A 150g tennis ball coming at a speed of 40m/s is hit straight back by a bat to a speed of 60m/s. The magnitude of the average force F on the ball, when it is constant for 5ms, is:
The change in momentum
Δp=m(vf−vi)
=0.150(60−(−40))
=0.150×100=15Ns
Thus, F=ΔPΔt=155×10−3=3×103N