Question

When two objects collide and stick together, what will happen to their speed, assuming momentum is conserved?

Answer 1

The correct answer is that when two objects collide and stick together, BOTH objects will change speed.
If they are moving in the same direction, the faster moving object will slow down and the slower moving object will speed up.
If they are moving in opposite directions the faster will slow down and the slower one will change direction.

Answer 2

They will move more slowly.

Step-by-step explanation:

When the two objects stick together, they can be treated like one larger mass. By increasing mass, and keeping momentum the same, velocity must decrease (a larger object moves slower if all other variables stay the same) by p = mv.