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pendulum to make electricity

 
Ted Taggart
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Does anyone have any information on using a pendulum to produce electricity?  PBS  did a special on alternative energies not used in US.  I have not heard much about since.
 
Michael Cox
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A pendulum does not make energy. It can, perhaps, be thought of as an energy store. You give it a shove and it gains some kinetic energy as it swings it converts that back to gravitational potential energy, then swings back as kinetic energy etc...  

The same energy added to the system remains, aside from losses due to air resistance.

If you try to extract energy from the system the pendulum will slow down rapidly then stop.
 
Douglas Alpenstock
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Respectfully, I'm not sure what the OP is asking.

Sure, you can extract electrical energy by moving a properly aligned conductor through a magnetic field (or a magnet past a conductor).

That could be done with a pendulum, if you wanted to. The efficiency would be incredibly low.

As Michael says above, the pendulum would impart its energy into the system (and many other losses) and then stop. So, a continuous input of mechanical energy would be required (wave action perhaps) to keep the pendulum moving and electricity flowing.

It would be a cool experiment, but I don't see a practical application.
 
Jordan Holland
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Yes, it will require a constant imput of energy, but sometimes it could be more practical than a constant rotary motion. I have seen those piezo-electric rods that are made to sway in the wind like trees, which would be an upside down pendulum. Waves could drive a pendulum generator. Tesla's magnet motor can work as a pendulum. It would be difficult to get much power without a large system due to the fact that the imput is not constant like a rotary system.
 
William Bronson
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Not all pendulums are the same.
A Foucault pendulum is powered by the movements of the earth itself.
If you built one out of permanent magnets,  and surround it with coils,  I think you could generate electricity.
Or the coil could be built into the pendulum and the chamber surrounded by permanent magnets.
Build it in a vacuum chamber to eliminate air resistant.
 
Douglas Alpenstock
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William Bronson wrote: Not all pendulums are the same.


Very true: the largest one we know of moves entire oceans up and down, daily.

Sometimes it's easier to connect the dots, from a practical point of view, when we define what the energy source is and what problem we want to solve.
 
Michael Cox
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William Bronson wrote: Not all pendulums are the same.
A Foucault pendulum is powered by the movements of the earth itself.
If you built one out of permanent magnets,  and surround it with coils,  I think you could generate electricity.
Or the coil could be built into the pendulum and the chamber surrounded by permanent magnets.
Build it in a vacuum chamber to eliminate air resistant.



Foucaults pendulum isn’t powered by anything is it? I thought is was simply an experiment that demonstrated the rotation of the earth. Set the pendulum swinging, wait an hour, see that the axis of motion has moved relative to the pendulum.

There is no addition of energy to the system, the ground moved relative to the pendulum axis.
 
Mike Haasl
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That's what I thought too Michael.  Here's a quote from Wikipedia:

Air resistance damps the oscillation, so some Foucault pendulums in museums incorporate an electromagnetic or other drive to keep the bob swinging; others are restarted regularly, sometimes with a launching ceremony as an added attraction.

 
Eric Hanson
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I kinda agree with Douglas.  I think it would be a fun experiment.  Maybe with a really heavy weight on the end it could “generate” some useable electricity for a period of time.  But of course, air & mechanical resistance pulse a counter force from the actual generation of electricity will draw down the movement of the pendulum fairly quickly.

Eric
 
William Bronson
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Excellent point about the "movement" of a  Foucaults pendulum.
I understood it more as it standing still and the earth moving, but I  wasn't sure and didn't want to complicate things.
The net result is the same.

Makes me wonder about one on the moon
 
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