# Homework Help: Angular elastic collision

1. Nov 4, 2007

### Jtappan

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

Two identical pucks are on an air table. Puck A has an initial velocity of 2.6 m/s in the positive x-direction. Puck B is at rest. Puck A collides elastically with puck B and A moves off at 2.50 m/s at an angle of +16.3° above the x-axis. What is the speed and direction of puck B after the collision? (Take angles above the x axis to be positive and below to be negative.)
____ m/s at -73.7 °

2. Relevant equations

?????????

3. The attempt at a solution

i know this is an elastic collision but i do not know how to solve it for a collision that is at an angle. I got the -73.7 because i know that if anythign is hit at an angle...the total angle of the 2 objects should add to 90 degrees. but how do i solve for the final velocity?

2. Nov 4, 2007

### Staff: Mentor

Momentum is conserved! Write equations for conservation of momentum for horizontal and vertical components.

3. Nov 4, 2007

### Jtappan

how do you do it for the initial and final? i dont understand this one