A baseball of mass m leaves a pitching machine of mass M ( where M includes the mass of the ball m) with a...?

Question

speed of V. the recoil speed of the machind after shooting the baseball is:...a) 2mv/(M-m) b) mv/M c) mv /(M +m) d) mv/ (M - m) e) 0...please show your steps for deriving this

Answer 1

As the system is at rest initially, its momentum both before and after firing is 0.

If U is the recoil speed of the machine:

- (M - m)U + mV = 0

U = mV / (M - m).