# One skater pushes another skater

1. Nov 24, 2004

### MATRIX-K-

I need to determine the masses of two skaters, who together weigh 120kg. They stand still opposite each other. Then they push each other away from away from each other. One of them gain the speed of 3,3m/s and the other one 2,1m/s.
How do you determine their masses?
I know it has something to do with impulses, but I can't figure it out...

2. Nov 24, 2004

### Integral

Staff Emeritus
This is a conservation of momtum proplem. Before the skaters push off their momentum is zero, so it must be after the push off. Can you take it from there?

3. Nov 24, 2004

### Sirus

$$\vec{p}=m\vec{v}$$
where p is momentum. As Integral said,
$$\vec{p}_{initial}=\vec{p}_{final}$$
You know initial momentum is zero, so find an expression for the final momentum and set it equal to zero.