# Homework Help: Momentum in 2 dimensions

1. Oct 21, 2007

### pinkyjoshi65

Well, I have been studying Work and Energy for a few days now. I started reading about momentum in 2 dimensions, but i can't seem to understand a thing! I would really appreciate it if someone could help me with this topic.

2. Oct 21, 2007

### hage567

3. Oct 22, 2007

### pinkyjoshi65

well. i have difficulty in understanding the problem questions. For eg: when 2 objects collide they go in different directions with different angles, and the question is to find the velocity. I have difficulty in analysing the problem and drawing the diagram with the vectors.

4. Oct 22, 2007

### cyprusad

There is a systematic way to deal with that kind of a problem.
First: Define a coordinate system. Choose a convenient x-axis and y-axis, such that you'd have to take the minmum number of components. And the ones that you take, can be easily found out using some trig.
Second: The component method works because, components are scalars, they can be added and subtracted like any other number. So write down the x and y components of the velocities of the bodies before (say a collision) and after. Use the conservation laws for conserving the momentum in the x axis and the y axis. (Never mix them up!)
Now, when you get the final components that you need, say a final velocity, or angle etc. Just change the components back to the vector form.

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