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Usage of perpetual motion in modern science

Let me say first that I am new to this and I ask this question simply by curiosity.

After some reading here and there, a perpetual motion device would be impossible because it violates the second law of thermodynamics.

Based on that, is it true to say that if we supply minimum energy (ex: constant electrical source) to the device, it would then be in perpetual motion?

Using this concept, one could build motors consuming very few energy?

How is this concept integrated in today's science?  Or is this concept not worth it?

I hope my question is clear considering my poor knowledge on the subject.

Thanks!
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TommySzalapski
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No. The electrical source would be consuming energy from an outside source and so would not be a true 'perpetual motion' machine.
The key is that even if you get energy from a moving device, you always lose more than you get.
There are some developments though that get energy from motion. For example, a shoe has been developed that produces electricity from your walking motion and could be used to power gadgets (like a watch)
http://www.energy-daily.com/reports/Company_says_shoes_can_power_gadgets_999.html

Of course the enery is coming from the food you ate (which gets its energy from the sun) so the energy isn't free.
>Based on that, is it true to say that if we supply minimum energy (ex: constant electrical source) to the device, it would then be in perpetual motion?

Yes and no.  It's a clock with a pendulum.  Or the human/stone powered millennium clock.

The point is, if you have to give it energy, the input source must be controlled.  How do you ensure that?  If you make some sort of universal input that takes all kinds of energy, there is significant loss in efficiency, requiring more power.  Then are parts that need maintained.

Plus, if you are always providing power, it's NOT perpetual motion.  It's a fake.
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^ that's the attraction of geothermal.  By the time the earth crust cools down, we won't be around...or will be smart enough to do something about it.

They're used now, but still require a bit of power to run the facilities.  A diamond mine up in Alaska uses one not for the heat, but to keep a dam frozen.
If we could get solar panels cheaper and more efficient, we'd have it made.
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In fact, I am not looking for perpetual motion but simply using it's concept to build something using the lowest energy possible.

Let's say I want to make a wheel spin.

Option 1 - I can use a common electric motor to make it spin using
Option 2 - Or I could use some kind of machine built based on "perpetual motion" concept to make that wheel spin

Option 1 will make the wheel spin using a certain amount of electricity (energy).  Spinning the wheel with option 2 adding electricity would use much less electricity, am I right?

What do you mean "based on perpetual motion"?
If you mean to harness energy from the spinning of the wheel to help power the wheel then no it actually won't help. Again, every time you convert energy from one form to another, you lose some of it.

If you make sure the wheel is really well balanced and oiled and do everything else to reduce the friction (ball bearings, etc) then it will run more efficiently. Perpetual motion was a myth before the science behind it was known as well as it is now.
For a spinning wheel, you'll need:

Extremely heavy and stable platform.
High edge mass (think of a discus, if you've ever been in track&field).
Low friction bearings.
No air (near vaccuum) to reduce air friction.
High rotational speed (30-50K rpm) with a lot of mass behind it to overcome loss due to friction.
Also, the high rate of spin gives you a longer running time between boosts.
Now, you need a containment shield in case something breaks.

Then, use an electromagnet to give the wheel a boost.  This can also be used to harness electricity if need be.  Makes a power backup without batteries or chemicals.
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I was listening to a radio program that talked about this a few days ago. Perpetual motion is either unachievable because of friction in the system or unpractical in that the designs some people come up with, for instance to use magnetic fields and carefully balanced pendulums, cannot work in practice.

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There is an interesting book on perpetual motion machines and 'free energy' machines, called 'The Scientist, the Madman, the Thief and their Lightbulb', by Keith Tutt.

It covers Tesla, Moray, Faraday and others and from basics to cold fusion. It includes obvious fakes to the curious to the inexplicable. Even if it doesn't answer your question - and amateur perpetual motion is probably an oxymoron - it's a good read.
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Thanks for all your comments.  It is a complex subject but it has been clarified nicely by all your comments.