# 2D Collision using momentum

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1. Nov 19, 2015

### member_216668

1. The problem statement, all variables and given/known data
Two equal mass hockey pucks undergo a glancing collision. Puck 1 is initially at rest and is struck by puck 2 travelling at a velocity of 13 m/s[E]. Puck 1 travels at an angle of [E18N] after the collision. Puck 2 travels at an angle of [E4S]. Determine the final velocity of each puck.

How do I solve the problem using conservation of momentum since I only have the two initial velocities?

2. Relevant equations
p=mv
mv1+mv2 = mv1f+mv2f

3. The attempt at a solution
I've tried to use the equations for a perfectly elastic collision

Last edited: Nov 19, 2015
2. Nov 19, 2015

### Isaac0427

If they have equal masses, shouldn't puck 2 have a velocity of 0 and not move in any direction? I'm not sure but that is how I learned the conservation of momentum.

3. Nov 19, 2015

### member_216668

Well puck 1 has a velocity of zero and puck 2 strikes it, so in the conservation of momentum equation, v1 cancels out along with all the masses. The equation then becomes v2 = v1f + v2f. With that equation there's two unknown values and one known, so I'm not sure how to solve it from this point on.

4. Nov 19, 2015

### SammyS

Staff Emeritus
That's only if it's a head-on elastic collision. This is a glancing collision.

5. Nov 19, 2015

### Ray Vickson

What does angle [E18N] mean? Is it 18 degrees north of east? Is is 18 degrees east of north? Is it something else?