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Bob S wrote:
3) If I (on frictionless ice skates) push off from an infinitely
rigid wall, there is no energy transfer between the wall and me. The
work energy theorem here guarantees that the work done by the wall's
push is numerically equal to my increase in kinetic energy, but it
says nothing to identify the source of my kinetic energy increase.
I should restrain myself. After all, Bob undoubtedly knows what he
means by this statement. And I can rephrase it into a valid statement
by replacing "work" by "pseudowork" everywhere above, that is the
normal force integrated over the displacement of the center of mass
of the skater while he's in contact with the wall. This is not the
work that appears in many formulations of the first law of thermo
however. -Carl
--
Carl E. Mungan, Asst Prof of Physics 410-293-6680 (O) -3729 (F)
Naval Academy Stop 9c, 572C Holloway Rd, Annapolis MD 21402-5002
mailto:mungan@usna.edu http://usna.edu/Users/physics/mungan/
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