# Homework Help: Two-d momentum

1. Oct 14, 2009

### physics10189

1. The problem statement, all variables and given/known data

On an air hockey table, two pucks collide with each other. Puck A have .05 kgand inital velocity of 5 m/s in the x direction. It collides with puck B which is initially at rest and has a mass of .1 kg. The collision is not a head on. AFter the collision, puck A flies of the north east direction with velocity of 3 m/s in an angle theta_A above the x axis. And Puck B flies off the south east direction with a velocity of 2.5 m/s in an angle of theta_B below the x axis. Find Theta_ A and theta_B

2. Relevant equations

3. The attempt at a solution

well I have two equations and three unknows I got

x direction: 0=.05kg*3m/s*sin(theta_a)+.1kg*2.5m/s*sin(theat_B)
and
y direction: m1*V=m1*v_1f*cos(theta_A)+m2*v_2f*cos(theta_B)

2. Oct 14, 2009

### willem2

I see only 2 unknowns. Just the 2 directions.

3. Oct 14, 2009

### physics10189

I think my equation in the y direction is wrong any thoughts?

4. Oct 14, 2009

### willem2

You swapped the x and the y directions.

What you wrote down for the y-direction is valid for the x-direction

what you wrote for the x-direction is nearly valid for the y-direciton, except
that you forgot $\theta_A$ is an angle above and $\theta_B$ below the x-axis