Question Regarding Momentum Lab

1. Oct 26, 2009

bleedblue1234

1. The problem statement, all variables and given/known data

We recently did a momentum lab in my AP Physics B class that involved a track with two carts. 1 of the carts was stationary on the track and the other was launched into it. We used sonar detectors at both ends of the tracks to find the velocity (and eventually calculate the momentum)....

My question is that on my lab I have a question that states: Why don't we need to take into account a case where the two carts would be rolling towards each other or the passive cart rams into the stationary (once active) cart to verify the law of conservation of linear momentum?

3. The attempt at a solution

I thought it had something to do with velocities being relative, and thus momentums being relative, therefore it is true in all cases? I am just a little confused...

2. Oct 26, 2009

tiny-tim

Hi bleedblue1234!
Yes, I'm a little confused too …

it seems to be begging the question.

Anyway, both conservation of momentum and conservation of energy work equally well in any inertial frame …

in other words, Galilean Relativity applies to inertial frames.