A 0.15kg cricket ball travelling at 20m s−1 is hit back along the same line with a speed of 30m s−1. If the bat is in contact with the ball for 0.010s, find the magnitude of the average force exerted by the bat on the ball.
a) 1.5×102N
b) 1.5×103N
c) 7.5×102N
d) 4.5×102N