At 9:07 AM -0600 12/21/01, Tom Wayburn wrote concerning Re: pseudowork:
Please define pseudowork, someone. (Carl?) I have never heard the
term used.
Work/Energy Theorem
delta KE = Work (net)
Let an astronaut of mass m be at rest near a space station of 'infinite' mass.
When the astronaut applies a constant force of F newtons while
'pushing off' over a distance d, find her change in KE.
The space station did NO work since there is no displacement of the
contact point.
Calculating the delta KE caused by the INTERNAL work done by the
astronauts muscles is a very complex problem and we can get the
'correct' answer by PRETENDING that the contact force has acted
through a distance equal to the CM displacement of the astronaut.
To let others know of our pretense, we use the term pseudowork.
Stepping forward from rest is another example. The floor does the
pseudowork that gives us our acceleration.
DO NOT use pseudowork in any problem that even vaguely resembles thermo!
I suspect that a more rigorous definition will be forthcoming.
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Chuck Britton Education is what is left when
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