A boy throws a 4-kg pumpkin at 8 m/s to a 40-kg girl on roller skates, who catches it. At what speed does the girl then move backward?

Answer 1

you have to use conservation of momentum, and conservation of energy on this. Remember the boy moves after he throws it also.

Answer 2

I don't understand how to work it?

Answer 3

Is it .8 m/s