In my article...

http://www.veljkomilkovic.com/Images/Merenja/Ronald_Pugh_Input-Output_Measurement_Mk5.pdf

I see I have made an error where I say "work done"  but as the footnote leads to the proper term, "power" there should have been no misunderstanding, but sorry if this has caused any confusion.

To define my usage of the nomenclature then...
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When a force acts upon an object to cause a displacement of the object, it is said that work was done upon the object.

Work is a force acting upon an object to cause a displacement.

An object which possesses mechanical energy is able to do work. In fact, mechanical energy is often defined as the ability to do work. Any object which possesses mechanical energy - whether it be in the form of potential energy or kinetic energy - is able to do work. That is, its mechanical energy enables that object to apply a force to another object in order to cause it to be displaced.

Power is the rate at which work is done. It is the work/time ratio.

The standard metric unit of power is the Watt. As is implied by the equation for power, a unit of power is equivalent to a unit of work divided by a unit of time. Thus, a Watt is equivalent to a Joule/second. For historical reasons, the horsepower is occasionally used to describe the power delivered by a machine. One horsepower is equivalent to approximately 746 Watts.

Regards

Ron

Sorry Ron, but this is not quite correct.

Forces that act inside a closed system stay in the system and are not called work. In order to qualify as work the force must act upon something outside the system.

That is why a pendulum on its own does NOT do any work until it drives something, in spite of the force fluctuations.

@ Ralph

Yes, pumping water is work. The weight going up and down at the end of a balance beam is not!

Hans von Lieven

Quote from: hansvonlieven on May 21, 2009, 06:07:15 PM
Sorry Ron, but this is not quite correct.

Forces that act inside a closed system stay in the system and are not called work. In order to qualify as work the force must act upon something outside the system.


Hans von Lieven

"The output has nothing to do with whether a system is closed. Systems without output are non-knowable through observation from the outside"

Ron

Quote from: hansvonlieven on May 21, 2009, 06:07:15 PM
Sorry Ron, but this is not quite correct.

That is why a pendulum on its own does NOT do any work until it drives something, in spite of the force fluctuations.

Yes, pumping water is work. The weight going up and down at the end of a balance beam is not!

Hans von Lieven

"An object which possesses mechanical energy is able to do work".

The pendulum is the system that possesses mechanical energy. The force acts on the hammer to displace it. The hammer is outside of the system.

Ron

"It was my intention to strain gauge Mk 5.3 (4) to see the input and output relation-ship; the output to be measured between the secondary arm and the counter weight, as in a Veljko Milkovic pendulum in hammer mode"

Quote from: i_ron on May 21, 2009, 02:40:27 PM

I see I have made an error where I say "work done"  but as the footnote leads to the proper term, "power" there should have been no misunderstanding, but sorry if this has caused any confusion.

ok
very good