read below?

Question

A stationary object receives a direct hit by another object moving toward it. Is it possible for both objects to be at rest after the collision? Explain.

Answer 1

Conservation of momentum

Answer 2

Sure.

The other response you have gives you an answer, but it's worthless without an explanation.

p, v = before collision
P, V = after collision

Cons. of momentum says:

p1 + p2 = P1 + P2

==> m1v1 + m2v2 = M1V1 + M2V2

If they are both to be at rest after the collision, then v2 = V2 = 0

==> m1v1 + m2v2 = 0
v2 = 0 (stationary target mass)

==> m1v1 = 0

BUT, that's not the only solution in these kinds of problems. If you regard M2 as being so much larger than m1, then you can say...

==> m1v1 = M1V2

If V2 ≈ 0

v1 ≈ M1/m2

(accounting for proper care of units)

In other words...if you roll a marble into a bowling ball.....the mass of the bowling ball (M2) is so great compared to the marble, that the velocity of the bowling ball (V2) is negligable, even tho physically it's nonzero, you can approx. it as zero.

Hope this helps.