Showing momentum will be conserved in moving reference frame

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Homework Help Overview

The discussion revolves around proving the conservation of momentum in both a stationary reference frame and a moving reference frame for a collision between two balls. The original poster presents the problem involving given masses and initial velocities, but expresses uncertainty about how to prove momentum conservation without final velocities.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the use of Lorentz and Galilean transformations to analyze momentum conservation in different frames. There is a focus on the relationship between initial and final velocities and the implications of having unknowns in the equations.

Discussion Status

The conversation is ongoing, with participants exploring different methods to approach the problem. Some guidance has been offered regarding the use of conservation principles, but there is no explicit consensus on a method or resolution at this point.

Contextual Notes

The original poster notes a lack of final velocities in the stationary frame, which complicates their ability to perform necessary transformations. The discussion also highlights the challenge of having multiple unknowns with limited equations available.

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Homework Statement


the question gives me the masses and initial velocities of two balls which collide elastically and asks me to prove that it the momentum will be conserved in both a still reference frame and a moving one.


Homework Equations





The Attempt at a Solution


i know that the momentum will be conserved in the moving frame because the final velocities will account for the change in the initial once due to the added velocity, however i don't know how to prove this without being given the final velocities.
 
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oh do i need to use lorentz transformations?
 
You have the initial and final velocities of everything in one frame (or you can figure them out). Transform those to the moving frame and see if things are still conserved. (I'd use Galilean transformations.)
 
I don't have the final velocities in the still frame though so how am I supposed to convert them? And I wouldn't I have to be given one of the final velocies? I have two unknowns and 1 formula
 
You have two unknowns and two conservation principles.
 
you mean energy and momentum? wouldn't they both give me the same thing since they both use m and v?
 
nevermind i got it thanks a lot
 

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