Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: [Phys-l] Magnetic force and work



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/