Finding Center-of-Momentum Frame

• bcoats
In summary, the conversation is about a student who is struggling with finding the relativistic cm frame for two particles. They have not received much guidance from their professor and are looking for a systematic method to solve the problem. Another person provides some resources and offers to help with specific problems. The student is grateful for the help.
bcoats
Hello,
My prof has assigned several homework sets dealing with finding the relativistic cm frame for two particles. However, he has not been quite up to speed with grading them, so I don't know if I really have a clue what I'm doing, and he hasn't gone over it much in class. I can't seem to glean much from A.P. French about the specific method for finding this frame.

I understand that it would be logical to use energy conservation to solve this problem. But I can't seem to find a systematic method for what should be a simple procedure.

Could someone give me a quick walkthrough on the simplest procedure for doing this? I just want to find out if I'm doing something wrong BEFORE I get these homeworks back.

Thanks much,
Ben

Here are a couple of references worth looking at, but you probably already have similar things in your text or notes. They are geared toward solving collision problems. In the most general case, you could have two particles with arbitrary momenta. You still have a total momentum as the sum of the two initial momenta, and the velocity of the center of momentum can be calculated from momentum and energy.

http://physics.nmt.edu/~raymond/classes/ph13xbook/node107.html#elasticenergy

http://teachers.web.cern.ch/teacher...ch/mbitu/applications_of_special_relativi.htm

Maybe if you posted specific problems with your attempted solutions someone could help you in more detail.

Last edited by a moderator:
Thanks!

Thanks a million for those links! The explanation was much more comprehensive and sequential than the one that my prof gave...or rather didn't give.

You're my savior, man!

Ben

1. What is the center-of-momentum frame?

The center-of-momentum frame is a reference frame in which the total momentum of a system is zero. In other words, the net momentum of all the objects in the system is balanced and there is no overall movement.

2. Why is it important to find the center-of-momentum frame?

It is important to find the center-of-momentum frame because it allows us to simplify the analysis of a system by removing any external motion and focusing only on the internal interactions between objects.

3. How is the center-of-momentum frame determined?

The center-of-momentum frame is determined by finding the reference frame in which the total momentum of the system is zero. This can be done by setting up equations to find the velocities of each object and then solving for the frame in which they all add up to zero.

4. Can the center-of-momentum frame change?

Yes, the center-of-momentum frame can change depending on the interactions and velocities of the objects in the system. If the objects in the system change their velocities, the center-of-momentum frame will also change.

5. How is the center-of-momentum frame used in physics?

The center-of-momentum frame is used in physics to simplify the analysis of systems with multiple objects and interactions. It allows us to focus on the internal interactions between objects and understand the behavior of the system without external influences.

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