Re: pinhole conservation of momentum vs energy

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From: Steven Eiger (eiger@montana.edu)
Date: Thu Nov 16 2000 - 08:57:06 PST 

Message-Id: <l03102800b639c102cccf@[153.90.150.107]>
Date: Thu, 16 Nov 2000 09:57:06 -0700
From: Steven Eiger <eiger@montana.edu>
Subject: Re: pinhole conservation of momentum vs energy

Nathania, I would start with an example like clay blobs of equal mass and
opposite velocity smacking together and coming to absolute rest, stuck
together. where has the kinetic energy gone? It is mostly still there,
but in individual molecules as they move quicker within the clay giving it
a warmer temperature. This is a start only, and potentially misleading.
Energy is shifted from one form to another. Light a match. Chemical
energy is converted into randomized kinetic energy, start a car - chemical
energy into non-random translational kinetic energy. Power plants, etc.
Eiger

>I have a student who understands that total energy is conserved. We
>have now gone onto the conservation of momentum. While she can see that
>mathematically momentum is conserved during an inelastic collision and
>kinetic energy is not, conceptually she is bothered. Since both
>momentum and KE are based on mass and velocity, how can momentum be
>conserved if the energy changes form. Anyone got a good way to attack
>this? Thanks
>Nathania
>
>
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Steven Eiger, Ph.D.

Department of Cell Biology and Neuroscience and the WWAMI Medical Education
Program
PO Box 173148
Montana State University - Bozeman
Bozeman, MT 59717-3148

Voice: (406) 994-5672
E-mail: eiger@montana.edu
FAX: (406) 994-7077

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