What Causes an Object to Stop after a Collision?

[mike_302]

Homework Statement

Two balls roll directly towards each other. The 0.25kg ball has a speed of 1.7m/s. The 0.18kg ball has speed of 2.5m/s. After the collision, the 0.25kg ball has reversed its direction and has a speed of 0.10m/s . What is the magnitude and direction of the 0.18 kg ball after hte collision?

Homework Equations

P(total)=P'(total)

The Attempt at a Solution

I know the answer... IT's 0 m/s . Further question though:

On a test, I'd be questioning that result. As I did when I first obtained it in the homework... So I thought to myself: Zero tends not to just come out of nowhere... There's usuall an indicator that it's coming. What is the indicator that one of the objects in a collision will stop? Is there any sort of indicator in this case?

Thanks!

Mike

 

[dx]

There's no special indicator in this case other than the momentum conservation calculation.