Re: Simple machine question?

[Larry Cartwright <exit60@CABLESPEED.COM>]

> cliff parker wrote:
> My question is, should the weight of the hangers and the meter
> stick itself be considered when calculating AMA?

The short answer is: Yes.

The concepts of IMA and AMA were developed by engineers to describe the
force ratio and distance ratio that contribute to determining a
machine's efficiency:
     ( Efficiency = Work_out / Work_in ).

Any force that contributes to the work done at either "end" of a
machine, including the weight of machine parts, has to be considered in
expressing the AMA.  Otherwise, the relationship which *defines* AMA and
IMA would not be true:
     ( AMA / IMA = Efficiency )

The laws of thermodynamics, work and energy tell us that Efficiency
always *must* be less than 1.  It is, of course, customary to multiply
Efficiency by 100 and express it as an Efficiency Percentage.

I was told in engineering school that the most efficient machine you can
buy is the old fashioned lever-style can opener, which has no moving
parts and uses the can rim as its fulcrum.  99.99% efficient.  Also
cheap and lasts for decades, a nearly perfect machine.

Best wishes,

Larry

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Larry Cartwright   <exit60@cablespeed.com>
Retired (June 2001) Physics Teacher
Charlotte MI 48813 USA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Information is not knowledge,
 knowledge is not wisdom,
 and wisdom is not foresight.
 Each grows out of the other
 and we need them all."
            (Arthur C. Clarke)
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