Sources of error in momentum conservation collision lab

[TaintedLove]

Hey everyone. In class, we conducted a lab to verify the law of conservation of momentum. On a frictionless surface (glass surface), we had to collide two masses and record the time, and then make calculations for the velocity... and using that, calculate the initial and final momentums and determine what type of collision had taken place. I'm having difficulty thinking of sources of errors for this lab... any help please? I'm not at all bright in physics so I'm having a lot of difficulty.. could there be air friction somehow? Something to do with the masses colliding? I don't know :(

The apparatus of our lab was as follows: http://i49.tinypic.com/2zyzb5c.png

 

[diazona]

Well, any time you measure something, there's always some error a.k.a. uncertainty involved because of the limits of your measurement device. So that's a start. Also, any factors you didn't account for could potentially be considered sources of error. That includes air friction as well as friction with the glass, and any energy released during the collision. Can you think of where else energy might have gone?