During the impact between a bat and a ball, the force on the ball varies as follows:
• It increases uniformly from 0 to 100N in the first 0.01s.
• Immediately after that, a constant backward force of 20N acts for 0.02s.
Ignoring all other forces, what is the net impulse on the ball?
a) 0.9Ns
b) 0.5Ns
c) 0.1Ns
d) −0.1Ns