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] |
Example: a block slides across a rough stationary table. How much of
the mechanical energy of the block was lost via work and how much via
heat?
I think it is possible to answer this question. But it is certainly
not "obvious" or "quite distinct" without considerable modeling,
analysis, and thought.
Integrate N#2 --> Int F*ds = Int ma ds
We _define_ Int F*ds as work and Int ma ds = 0.5mv^2 as KE == energy -- by
definition.
Some of this work we call PE and we lump the PE and the KE together -- This
is not always helpful in an intro class.
Thus the work done on the system = - the work done on the applicator.
Now some on this list will want to use "enhanced" language but this is
quite adequate for an intro class -- and beyond.
I've been doing a survey, talking to physicists. Not physics
teachers, but people who do physics research for a living.
-- I ask them for the technical definition of "work".
100% of them answer "Force dot distance".
-- I ask them for the corresponding definition of "pseudowork".
100% of them give me funny looks.
0% have ever heard of the term before.
(Nearly 100% of them fall back to a non-technical
definition: pseudowork is what management does :-)