# Homework Help: Question about some physics, moving obstacles.

1. Nov 29, 2005

### Pytagoras

Hi, first i would like to start of by saying that i am norwegian, so my english skills is not so good. But anyway, im having this test tomorrow and i need some help! Its about physics! I translated the task as good as i could!

To sleds with elastic bumpers collides with eachother on a air-cussion course. Sled A's mass is 0,1kg, and sled b's mass is 0,4 kg. After the impact, sled A is moving at 0,5m/s and sled B is standing still. Calculate the speed of the to sleds before the impact.

Thanks for all answears!
If something is badly explained, please let me know!

2. Nov 29, 2005

### goulio

You need to find two unknowns, so you need two equations. The key word is "elastic", this means that both energy and momemtum are conserved. From this statement you can easily find two equations.

But one thing is not clear, you need to know how the sleds collide, do they collide head on, or in any other way?

Hope this helps!