13-05-2005, 05:22 PM
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The message
from (Nick Maclaren) contains these words:
In article ,
Jaques d'Alltrades writes:
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| A foot pound is very precise, and is that amount of energy required to
| shift the mass of one pound the distance of one foot - but how you would
| measure it in the 'back garden lab' I don't know.
Er, you DID learn some elementary physics at school, didn't you?
I did 'A'-level physics when it was an exam...
Moving a mass of a pound the distance of a foot isn't a measure
of energy. At a naive guess, it would mean a foot-pound(force),
a.k.a. a foot-poundall, or a foot-pound(weight). But another,
equally important, question is how it is specified to be measured
(which is where my remark about BHP comes in).
If you drop a pound weight (weighed in air) the distance of one foot, it
will dissipate one foot pound of energy when it comes to rest.
Accordingly, if you raise a pound weight the distance of one foot, tou
have to apply one foot pound of energy to accomplish it.
However, if you are doing delicate measurements, you need to eliminate
buoyancy, air resistance and friction, hence my reference to mass.
I would have no difficulty measuring it at home, in any of several
different ways,
Well, I wouldn't be quite so sanguine, unless I had access to a lot more
bits and bobs than I do.
and how to do so would make a nice open elementary
physics examination question. No, I don't approve of the modern
approach of close examination questions or, worse, box ticking.
Nor do I. Without any study I 'passed' a trial RAE (Rajo Amateur Exam)
just by discarding answers which were impossible, and choosing the most
likely of what was left. OK, I wouldn't have got a distinction, but it
was by no means a scrape-in.
--
Rusty
Open the creaking gate to make a horrid.squeak, then lower the foobar.
http://www.users.zetnet.co.uk/hi-fi/
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