# Homework Help: Oblique Elastic Collisions

1. Jan 29, 2010

### kingjoshie

1. The problem statement, all variables and given/known data
I am unsure about how to go about solving an oblique elastic collision question, I understand that momentum is conserved and how to calculate momentum but unsure as to how to calculate the vectors.

The question is : A 45g marble collides with an identical stationary marble, and continues at 55 degrees to it's original direction. The collision is perfectly elastic. What is the angle between the direction taken by the target ball and the original direction of the incident ball?

2. Relevant equations p=mv, not too sure how other equations are set up.

3. The attempt at a solution I calculated the force of momentum of both the balls and the direction but drew a total blank.

2. Jan 30, 2010

### Staff: Mentor

Momentum is conserved. Write a momentum conservation equation, realizing that momentum is a vector. (Hint: Draw a vector diagram illustrating that equation.)

The fact that the collision is elastic will give you another conservation equation. Combine those two equations to figure out the angle between the final velocities of the marbles.

3. Jan 30, 2010

### kingjoshie

Hi, Thanks a lot, I was having a hard time understanding that part but you definitely cleared it up.