when two objects collide can they both be at rest?

Question

If two objects collide and one is initially at rest, is it possible for both to be at rest after the collision? Is it possible for one to be at rest after the collision? Why/how???

Answer 1

action and reaction means there should always be some follow through motion or rebound.
only if the energy is fully transferred will one object remain staionary.
take a desk toy - the 5 swinging balls on cord.
the first ball is pulled back and is released to hit the staionary other 4 balls.
on impact the kinetic energy of the first is transferred to the other through one another until the energy is released through the chain on to the 5th. this ball has no object to transfer to and thus moves away.
you see a collision of one object into 4 others and 3 remain still.
so it is possible for 2 objects to collide and remain stationary however, this is not the perfect world so you will alway see a little rebound on the desk toy.

Answer 2

1) Yes, it is possible if the object being hit cannot overcome any frictional force acting on it (like someone falling from a building...there's probably no bounce back up). Because momentum and/or energy must be conserved, it gets transferred/absorbed to something else (i.e. the ground or a wall).

2) It is possible for one object to be at rest after the collision. If you have an elastic collision, energy must be conserved.
The object that's moving will hit the other object, transfer its momentum and energy and then stop. While the object being hit, will begin moving since it now has kinetic energy.

Answer 3

>If two objects collide and one is initially at rest, is it possible for both to be at rest after the collision?

Only if the moving object has zero mass and the resting object has positive mass. So on general principle, no. It is however possible for two objects both with positive mass to both be at rest after the collision provided that both are moving before the collision.

Answer 4

> it possible for both to be at rest after the collision?

Use the principle of conservation of momentum. Consider the total momentum of both objects; and remember that it has to be conserved (i.e. has to be the same before & after).

Before collision: total momentum is (zero or nonzero?)
After collision: total momentum is (zero or nonzero?)

That should give you your answer.