Perfectly elastic collision

southernbelle

1. The problem statement, all variables and given/known data
In an isolated system, cart1 (with mass = 1 kg and vi1 = 2) has a perfectly elastic collision with cart2 (with mass = 2 kg and vi2 = 0). Find the velocity of cart1 and the velocity of cart2 after the collision.


2. Relevant equations
1/2m₁v_i1² + 1/2m₂v_i2² = 1/2m₁v_1f² + 1/2m₂v_2f²

m1vi1 + m2v2i = m1v1f + m2v2f


3. The attempt at a solution

I plugged in all of the numbers.

For momentum I got
2= V1f + 2 V2f

For kinetic energy I got
4 = V1f² + 2V2f²

Next I solved for V1f and plugged it into the equation.

I just need some confirmation that my answer is right.

It doesn't seem correct.

I got:
V2f = 2
V1f = -2

Hootenanny

You could check your answers yourself. Do they satisfy both the kinetic energy and momentum equations?

southernbelle

No, they don't. You're right that was an easy way to check myself.