Why do we not discuss perpetual motion machines (PMM)?

  • Thread starter PughBear
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In summary, perpetual motion machines (PMM) are not discussed because they violate the laws of thermodynamics and are considered impossible to achieve. These machines are designed to continuously generate energy without any external source, which goes against the first or second laws of thermodynamics. The first law states that energy cannot be created or destroyed, only transformed, while the second law states that energy naturally flows from a higher concentration to a lower one, resulting in a loss of usable energy. The concept of PMM has been a subject of fascination and debate for centuries, but it has been deemed unfeasible due to the basic principles of physics.
  • #1
PughBear
How did you find PF?
I found PF by Binging energy produced by spring rotational energy and found a link here.
https://www.physicsforums.com/threads/spring-energy-to-rotational-energy.499140/

I am inclined to think there is something that came be thought out to get more energy out of than what you put in. Consider a simple wind up watch that you wind effortlessly for a few seconds by hand, but the energy used can have a watch 'run' for days! What about a large scale of this considering gear ratios, kinetic and inertia energy with added weights and movement also. Has anyone really did any kind of physics study on this?
 
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  • #2
PughBear said:
I am inclined to think there is something that came be thought out to get more energy out of than what you put in. Consider a simple wind up watch that you wind effortlessly for a few seconds by hand, but the energy used can have a watch 'run' for days!
The energy used to wind up the watch is not effortless, and it's greater than the energy used to turn the hands.

PughBear said:
What about a large scale of this considering gear ratios, kinetic and inertia energy with added weights and movement also. Has anyone really did any kind of physics study on this?
Yes, lots of people have. Aside from the fact that it takes more energy to wind the mainspring of the clock than what is used to turn the hands, what you're thinking about violates the second law of thermodynamics. People who think they have come up with a perpetual motion machine, or an over-unity device (a device that produces more energy than it takes to create that energy) evidently do not understand this law of thermodynamics. In addition, discussion of PMMs and over-unity devices is not permitted at this site.
 
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  • #3
PughBear said:
How did you find PF?: I found PF by Binging energy produced by spring rotational energy and found a link here.

Has anyone really did any kind of physics study on this?
Welcome to PF.

As Mark says, such discussions are off-limits here at PF. Here is a good Insights article to help you understand the issues. Enjoy PF! (this Intro thread is now closed)

https://www.physicsforums.com/insights/why-we-dont-discuss-perpetual-motion-machines-pmm/
 

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