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Re: [Phys-l] force or mass



I'll 'stick to my guns' too. Clearly some groups use the pound as mass, other groups (engineers and intro physics textbook writers) take it as force. I will continue to go with the engineers and intro books. Students come to us with the clear knowledge that WEIGHT is measured in pounds. We then insist that weight is a force. Therefore, keeping pounds as a unit of force (with slugs the mass) follows the metric format of Newtons, kilograms. Again the foot-pound becomes very confusing (and the wrong basic units) if pound is mass. Of course, as Bernard hints at, using strictly metric units would solve the problem, but in intro physics courses one of the most powerful pedagogical tools we have is to work from and with what the students already 'know'. They 'know' pounds to be weight!

Rick

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Richard W. Tarara
Professor of Physics
Saint Mary's College
Notre Dame, IN
rtarara@saintmarys.edu
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New lab simulation--Calorimetry
PC & Mac
www.saintmarys.edu/~rtarara/software.html
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----- Original Message ----- From: "Bernard Cleyet" <bernardcleyet@redshift.com>


The exception is torque units.

bc, "sticking to his guns".

p.s. of course, this has been mainly ATA, much decried by JD, OTOH,
if the US govt. (all powerful) claims a # is a measure of mass then
it is; nicht wahr?

p.s. NBS definition of the pound:

http://www.ngs.noaa.gov/PUBS_LIB/FedRegister/FRdoc59-5442.pdf