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Re: mechanical equivalent of heat



in research 2ppm is common -- A Sr. thesis student at UCSC recently built
a temperature controller with a one millidegree error sensitivity. People
who study critical effects use these things.

Vernier's has (in your range of interest) 0.03 C deg. resolution.
http://www.vernier.com/probes/temp.html

Ten strokes ~ 15% resolution, a hundred -- 2% -- "doable"

bc

P.s. He built it to control a heater to study the critical point of, I
think, butane.

Ludwik Kowalski wrote:

OOPS, A TYPING ERROR WAS CORRECTED dT=0.018 degree

Ludwik Kowalski wrote:

kyle forinash asked:

Does anyone have a simple mechanical equivalent of heat
laboratory exercise (1st year undergrad level)?

I know of two; lead shot falling in a tube (which has horrible
accuracy) and the 'calorimeter on a crank' appratus (pretty
costly). I don't like either. ...

Somebody who has access to a shop can produce something
like this. It is a sealed iron tube (3 kg) and an iron piston (10 kg)
inside, with some air. The piston can travel 1 meter from one
end to another; it has holes allowing air to sip during a vertical
fall. Suppose the tube, well insulated with styrofoam, has a
mechanical release system to trigger the fall of the piston. By how
much should the temperature increase? PE decreases by 98 J
producing 23.4 calories of heat. Assuming all of it goes to 13
kg of iron the expected dT is 0.018 degree (in a single shot).
Can such dT be measured with a thermister to within ~1%
accuracy? I do not know.
Ludwik Kowalski