Momentum Physics Problem?

Judy (mass 40 kg), standing on slippery ice, catches her leaping dog (mass 15 kg) moving horizontally at 3 m/s. Show that the speed of Judy and her dog after the catch is 0.8 m/s.

Ok, so I am assuming that v initial is 3 m/s and v final is 0.8 m/s.

Also, Judy's mass plus the dog's mass = 55 kg.

What equation should I be using?


final velocity of Judy and dog together V = intial momentum of dog / total mass

ie., V = 3 x15 / 40+15 = 45 / 55 = 0.818 m/sec. proved.


In an ELASTIC collision use the formula m1v1 + m2v2 = m1v1 + m2v2 the left hand side is initial and right hand side is final