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[Phys-L] Re: collision question



Certainly, the momentum of the entire closed system is conserved. So is the
energy. This does not preclude dissipation. Dissipation of energy does not
imply energy destruction - neither does dissipation of momentum.
(The original system momentum is not necessarily zero, but that is a red
herring)

Bob Sciamanda
Physics, Edinboro Univ of PA (Em)
http://www.winbeam.com/~trebor/
trebor@winbeam.com
----- Original Message -----
From: "Scott Goelzer" <s.goelzer@COMCAST.NET>
To: <PHYS-L@LISTS.NAU.EDU>
Sent: Friday, February 18, 2005 12:00 PM
Subject: Re: collision question


| On Feb 18, 2005, at 9:30 AM, Bob Sciamanda wrote:
|
| >
| >
| > Two electrons flying by (while repelling) each other, generate E/M
| > radiation
| > fields which carry away momentum/energy. This momentum/energy is lost
| > to
| > the two particle system and is ultimately absorbed and thermalized by
| > the
| > lab walls and/or other objects. Why can I not say that
| > momentum/energy has
| > been dissipated by the two particle system?
| >
| >
|
| I'll give it a shot.
| Initially there was no momentum , then as the electrons pushed away
| from each other there is still zero total momentum since p is a vector.
| If the room is included in the system, then after the electrons
| interact with the room, the total momentum remains zero and the CM is
| not changed. Individual momentums did not dissipate , they cancelled.
|
| Scott
|
|
|
| **********************************
| Scott Goelzer
| Physics Teacher
| Coe-Brown Northwood Academy
| Northwood NH 03261
| 603-942-5531e218
| sgoelzer@coebrownacademy.com
| **********************************
|
|