What Are the Final Velocities of Hockey Pucks After a Glancing Collision?

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Homework Help Overview

The discussion revolves around a problem involving two equal mass hockey pucks undergoing a glancing collision. Puck 1 is initially at rest and is struck by puck 2, which is moving at a velocity of 13 m/s towards the east. After the collision, puck 1 moves at an angle of 18 degrees north of east, while puck 2 moves at an angle of 4 degrees south of east. Participants are exploring how to apply the conservation of momentum to determine the final velocities of each puck.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the application of conservation of momentum, questioning how to handle the two unknown final velocities. Some express confusion about the implications of equal masses on the velocities post-collision. Others raise questions about the interpretation of the angles given in the problem.

Discussion Status

The discussion is ongoing, with participants offering insights into the conservation of momentum and the nature of glancing collisions. There is a recognition of the complexities involved due to the angles and the need for further clarification on the problem setup. Multiple interpretations of the collision dynamics are being explored.

Contextual Notes

Participants note potential confusion regarding the definition of the angles provided in the problem, specifically whether the angle [E18N] is interpreted as degrees north of east or east of north. There is also mention of the distinction between head-on and glancing collisions, which affects the application of momentum conservation principles.

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Homework Statement


Two equal mass hockey pucks undergo a glancing collision. Puck 1 is initially at rest and is struck by puck 2 traveling 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?

Homework Equations


p=mv
mv1+mv2 = mv1f+mv2f

The Attempt at a Solution


I've tried to use the equations for a perfectly elastic collision
 
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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.
 
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.
 
Isaac0427 said:
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.
That's only if it's a head-on elastic collision. This is a glancing collision.
 
member_216668 said:

Homework Statement


Two equal mass hockey pucks undergo a glancing collision. Puck 1 is initially at rest and is struck by puck 2 traveling 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?

Homework Equations


p=mv
mv1+mv2 = mv1f+mv2f

The Attempt at a Solution


I've tried to use the equations for a perfectly elastic collision

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

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