# Elastic 2-D Collisions without given masses?

1. Dec 14, 2008

### kelseymclean

1. The problem statement, all variables and given/known data
In a classic curing shot, the shot stone, traveling at 6.0m/s [E] hits a stationary stone. The target stone is propelled at a velocity of 2.0 m/s [East30degreesSouth] What is the velocity of the shot stone after the collision? (Assume the collision is fully elastic)

2. Relevant equations
V11 =((ΔmΔV)/ MT) + V2
V21 = ((-2*M1*ΔV) / MT) + V2

3. The attempt at a solution
I don't know how to figure out this question without a mass
Do I go through the solution and just sub in a value for m? The problem is that the result will be different if the curling stones have different masses...

Last edited: Dec 14, 2008
2. Dec 14, 2008

### hage567

Since the masses of the stones are the same, I would think it would cancel out.

3. Dec 14, 2008

### kelseymclean

Thats just it, it doesn't say they are the same. It doesn't specify what the mass is of either of the stones..

4. Dec 14, 2008

### glueball8

"a classic curing shot" so its the same mass.

5. Dec 14, 2008

### tiny-tim

6. Dec 14, 2008

### kelseymclean

Oh, I didn't realize that in a classic curling shot, they have the same mass... We've done examples in class where the rocks have the same mass, and some have different...
Thanks for your help everyone :)