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The RHS of the CM work-energy system is the change in the CM kinetic
energy (1/2 the system mass times the square of the CM speed).
The KE of a mechanical system can be resolved into this (CM) kinetic
energy plus the kinetic energy of the system constituents as
measured from
the CM frame. This latter ("internal") ke is not included in the
aforementioned WE theorem. The theorem is simply (the
integral of) F=ma
applied to the motion of the system CM.
----- Original Message -----
From: "RAUBER, JOEL" <JOEL_RAUBER@SDSTATE.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Tuesday, October 30, 2001 1:40 PM
Subject: Re: ENERGY WITH Q
and a "back
1) It's not true. Consider a device with a "front wheel"
is zero. Thewheel". Starting from rest, I spin up the wheels,
counter-rotating. The
net torque around the CM is zero. The motion of the CM
kinetic energyconjectured expression above is zero squared. Yet the
illustrates the pointincreases.
I think this is the best gedanken device yet that
John
D is making. Any comments from others regarding this example?
Joel R.