A 3.32 kg mud ball has a perfectly inelastic collision with a second mud ball that is initially at rest. The composite system moves with a speed equal to one-eighth the original speed of the 3.32 mud ball. What is the mass of the second mud ball?

Answer 1

Conservation of momentum:

(M1+M2)V1/8 = M1*V1-M2*0
Multiply both sides by 8/V1:
M1 + M2 = 8M1
3.32 + M2 = 8*3.32
M2 = 8*3.32 - 3.32 = 23.24 kg.