a 75 kg object traveling at 4 m/s collides with and sticks to a 125 kg object initially at rest, what is the final velocity of the two objects?

Answer 1

initial momentum = 75 * 4
final momentum = (75+125) * v ===== in same direction
but we all know, momentum is the same before and after
so
v = (75*4) / (75+125)