Question

A baseball player uses a pitching machine to help him improve his batting average. He places the 73.9 kg machine on a frozen pond. The machine fires a 0.118 kg baseball horizon-

tally at a speed of 40.8 m/s. What is the magnitude of the recoil velocity

of the machine?

Answer in units of m/s.

Answer 1

According to the law of conservation of momentum, the magnitude of the recoil velocity of the machine is equal to the magnitude of the initial velocity of the baseball, since the total momentum of the system (the machine and the baseball) remains constant. In this case, the magnitude of the initial velocity of the baseball is 40.8 m/s, so the magnitude of the recoil velocity of the machine is also 40.8 m/s. Answer: \boxed{40.8}.