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Re: vector quantities and energy



Ed Schweber (edschweb@ix.netcom.com)
Physics Teacher at The Solomon Schechter Day School, West Orange, NJ
To obtain free resources for creative physics teachers visit:
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-----Original Message-----
Hi:

It seems that one important reason that energy should be defined as a
scalar and momentum as a vector is to account for why KE is not conserved in
a typical collision while momentum always is conserved. The increased random
molecular vibrations caused by the collision absorb macroscopic KE. But they
don't absorb momentum because on average these motions are in opposite
directions and therefore add up to a zero net momentum - precisely because
momentum is a vector.

Ed Schweber