Question

While sitting motionless in a 5 kg friction free wagon, an 80kg clown catches a 15 kg cannonball traveling horizontally at 20 m/s. After the cannonball is caught, at what speed do the clown, wagon, and ball move?

Answer 1

Momentum is conserved
15*20= initial momentum =300
total mass after being caught = 100 
momentum=mass*velocity
thus dividing the momentum by total mass we get the velocity of 3 m/s