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Re: irreversible lifting

Hi --

I asked:

OK, how irreversible is [lifting a weight]?
What percentage of the work *must* be done
irreversibly? Can you state a positive lower bound?


To which at 06:53 AM 11/1/99 -0600, brian whatcott answered:

a 2000 Calorie p.d diet (=8.4MJ)
...
Efficiency = 100 X 5.2/8.4 = 62%

Hehehe...I hope this started your day with a smile. :-)

Yup :-)


Now, would anybody care to try for a non-comical estimate?
In particular, suppose that rather than lifting the weight by muscle-power
alone, suppose we lift it using various arrangements of counterweighted
levers, pulleys, springs, and gas-pistons. What then is the minimum
percentage of work that must be done irreversibly?

Can anybody come up with a nontrivial lower bound?

______________________________________________________________
copyright (C) 1999 John S. Denker jsd@monmouth.com