(a) The magnitude of the impulse is equal to the change in momentum .
J=mν−m(−ν)=2mν=2(0.140kg)(7.80m/s)=2.18kg⋅m/s
(b) Since in the calculus sense the average of a function is the integral of it divided by the corresponding interval, then the average force is the impulse divided by the time Δt .Thus, our result for the magnitude of the average force is 2mν/Δt With the given values, we obtain
Favg=2(0.140kg)(7.80m/s)0.00380s=575N