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Topic: Perpetual Motion II (Read 899 times) |
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James Fingas
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Perpetual Motion II
« on: Aug 21st, 2003, 1:21pm » |
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Background: Air pressure is due to many air molecules hitting and rebounding from a surface. The air molecules move because they are hot. Taking the average force of a very large number of air molecules over a period of time gives a very steady force, proportional to the area over which the air is.
Question: What would happen if you created a surface which was small enough that there weren't many air molecules hitting it?
Answer: The force of air pressure would no longer be constant; it would have measureable spikes and dips.
Question: What would happen if you created a very small surface and attached it to a very small spring?
Answer: The surface would be bounced around by air molecules.
Question: What would happen if the surface was made out of a magnetized material, and you put a small coil of wire nearby?
Answer: You would get a time-varying voltage on the coil.
Question: What if you extracted the energy created by the coil?
Answer: You would turn the heat of the air into electrical energy.
Question: Isn't this disallowed by the laws of thermodynamics?
Answer: Of course!
Why would/wouldn't this idea work?
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Kelvin
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Re: Perpetual Motion II
« Reply #1 on: Aug 22nd, 2003, 4:58am » |
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thermoelectric'ity noun electricity developed by the unequal heating of bodies, especially between a junction of metals and another part of a circuit.
Now taking the above into consideration, your theory could still work if it is based on the time-varying voltage you would get on the coil.
My opinion is that you would progress from the laws of Thermodynamics, to the laws of Thermoelectricity.
Your views? 
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James Fingas
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This device doesn't depend on the thermoelectric effect, which relies on differing attractions for electrons in different metals at different temperatures (or something like that).
The thermoelectric effect doesn't break the laws of thermodynamics, because you need two heat sinks (one hot, one cold), and heat is transferred from the hot to the cold as a side effect of electricity generation.
In this case, heat is extracted from just one heat sink to generate electricity, which is definitely forbidden.
Ooh! An attachment feature! Just have to try it out! Here's a diagram showing a thermoelectric apparatus.
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| « Last Edit: Aug 22nd, 2003, 6:48am by James Fingas » |
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TenaliRaman
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Re: Perpetual Motion II
« Reply #3 on: Aug 22nd, 2003, 11:45am » |
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i have some doubts i would like to clarify.They may sound totally idiotic and if so please pardon my ineptness at swallowing the above details.
on Aug 21st, 2003, 1:21pm, James Fingas wrote:
Question: What would happen if you created a surface which was small enough that there weren't many air molecules hitting it?
Answer: The force of air pressure would no longer be constant; it would have measureable spikes and dips.
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Do we have to assume that the system is totally isolated?(Bcos i can think of some factors which might largely affect the surface because of its small size.)
on Aug 21st, 2003, 1:21pm, James Fingas wrote:
Question: What would happen if you created a very small surface and attached it to a very small spring?
Answer: The surface would be bounced around by air molecules.
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Shouldn't the tension in the spring be accounted for?
on Aug 21st, 2003, 1:21pm, James Fingas wrote:
Question: What would happen if the surface was made out of a magnetized material, and you put a small coil of wire nearby?
Answer: You would get a time-varying voltage on the coil.
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Is there a change of flux produced here??
on Aug 21st, 2003, 1:21pm, James Fingas wrote:
Question: What if you extracted the energy created by the coil?
Answer: You would turn the heat of the air into electrical energy.
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No doubts here!
on Aug 21st, 2003, 1:21pm, James Fingas wrote:
Question: Isn't this disallowed by the laws of thermodynamics?
Answer: Of course!
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No doubts here either!
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James Fingas
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on Aug 22nd, 2003, 11:45am, TenaliRaman wrote:| i have some doubts i would like to clarify.They may sound totally idiotic and if so please pardon my ineptness at swallowing the above details. |
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No question is stupid. I don't know whether this thing works or not, but I generally believe in the laws of thermodynamics.
Quote:| Do we have to assume that the system is totally isolated?(Bcos i can think of some factors which might largely affect the surface because of its small size.) |
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If there is some factor I'm not thinking about that would prevent the surface from moving, that would explain why it doesn't work. What are you thinking about?
Quote:| Shouldn't the tension in the spring be accounted for? |
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Think of a square piece of metal attached to a thin springy piece of metal. Whatever tension is in the spring, the square piece should still bounce around wildly under time-varying forces (e.g. in the wind).
Quote:| Is there a change of flux produced here?? |
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Yes. The magnetic field produced by the magnetized surface moving around should change the flux through the coil over time. Unless there's something I'm forgetting...
If it makes it any clearer, here's a picture of what I was thinking:
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| « Last Edit: Aug 25th, 2003, 9:25am by James Fingas » |
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Icarus
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Re: Perpetual Motion II
« Reply #5 on: Aug 22nd, 2003, 3:35pm » |
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on Aug 21st, 2003, 1:21pm, James Fingas wrote:Question: What would happen if you created a surface which was small enough that there weren't many air molecules hitting it?
Answer: The force of air pressure would no longer be constant; it would have measureable spikes and dips. |
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on Aug 22nd, 2003, 11:45am, TenaliRaman wrote:| Do we have to assume that the system is totally isolated?(Bcos i can think of some factors which might largely affect the surface because of its small size.) |
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Whatever the failing is, it is not here. Brownian motion is a well-known phenomenon.
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SWF
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Re: Perpetual Motion II
« Reply #6 on: Aug 22nd, 2003, 5:10pm » |
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I don't think that device violates the 2nd Law unless it still operates when the gas is cooled below temperature outside the device. In that case heat would be tranferred from the cooler to the warmer body (via the wire) without external work.
When the gas temperature cools to the external temperature (assuming the wire runs to the outside since it is delivering work there) it will reach equilibrium because of thermal noise. This noise is random current fluctuations in the wire due to temperature dependent electron motion. This causes the generator to work in reverse as a motor: the fluctuations in current cause a magnetic field which makes the paddle oscillate. Since the paddle is moving, when molecules hit it they can gain momentum like a ball being hit with a tennis racquet or lose it depending on relative motion. The relative temperatures of the gas and wire will determine which way energy tends to be transferred, and it should balance when temperatures are the same.
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TenaliRaman
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Re: Perpetual Motion II
« Reply #7 on: Aug 23rd, 2003, 4:13am » |
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Thanks for the clarification James.
Now as i think of this,i try to think as to where it violates the law of thermodynamics.The process seems irreversible
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James Fingas
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Re: Perpetual Motion II
« Reply #8 on: Aug 25th, 2003, 9:35am » |
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on Aug 22nd, 2003, 5:10pm, SWF wrote:When the gas temperature cools to the external temperature (assuming the wire runs to the outside since it is delivering work there) it will reach equilibrium because of thermal noise. This noise is random current fluctuations in the wire due to temperature dependent electron motion.
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That's an interesting thought. But how about this: consider a baseline amount of thermal electron motion in the wire, causing baseline random current fluctuations. When you attach the 'generator', you add a random signal based on the movement of gas in the chamber. The total electrical current should be larger than the baseline in this case. Now what if the load was a resistor? Because the electrical current fluctuations are larger than baseline, it should heat up just a little more than the ambient temperature.
The heat from the resistor might propogate down the wire back to the generator, but then you have already violated the second law: the wire/resistor/generator assembly is hotter than the gas.
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