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Questions tagged [perpetual-motion]

Perpetual motion describes "Motion that continues indefinitely without any external source of energy; impossible in practice because of friction." It can also be described as "the motion of a hypothetical machine which, once activated, would run forever unless subject to an external force or to wear". There is a scientific consensus that perpetual motion in an isolated system would violate the first and/or the second law of thermodynamics.

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Are vibrating strings in string theory perpetual motion?

I have never learned string theory, so please forgive me if my question sounds naive or obvious, but I would like to know and I am most likely wrong. As far as I know, strings vibrate in different ...
Tachyon's user avatar
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Would a diode more ideal than Shockley diode equation violate the second law of thermodynamics?

The Shockley diode equation describes the behavior of all diodes extremely well. Semiconductor p-n diodes and Schottky diodes are described by the very same equation. Furthermore, it applies to light ...
juhist's user avatar
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Why doesn't gravity causing the adiabatic lapse rate violate the laws of thermodynamics?

I'm looking to fully understand how the adiabatic lapse rate works and why it causing warmer air doesn't violate the laws of thermodynamics. My understanding is as follows: consider a parcel of air ...
Cloudyman's user avatar
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2 answers
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What’s wrong with this idea for an energy generator? [closed]

Okay I know a perpetuum mobile is impossible, so I think this should be wrong. I thought about heat pumps with a COP of 3.5, which is like 350% efficiency compared to a simple electrical resistor. Now ...
user1009013's user avatar
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2 answers
157 views

What makes a perpetual motion machine of the second kind actually “perpetual”?

As I understand it, a perpetual motion machine does continuous work without additional energy input. If a perpetual motion machine of the second kind exists, it violates the second law of ...
Alex Walczak's user avatar
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1 answer
382 views

Can land breezes be an example of perpetual motion?

Since perpetual motion refers to a never-ending motion with no external energy provided whatsoever, can land breezes or sea breezes be an example? Or perhaps even trade winds, since this, I believe, ...
Mel's user avatar
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Using directed centrifugal force to create continuous acceleration [closed]

This is something that I've been curious about for a while now, and please understand I'm not a physicist by trade. I began this thought experiment thinking about how I've seen vibrations generated in ...
rubixibuc's user avatar
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Power density of free space under expansion

Back when I owned a consulting business, I had to occasionally refuse attempts to engage me to help someone complete "just a detail or two" on their perpetual motion machine. Usually I tried ...
TimWescott's user avatar
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Parallel plate capacitor infinite energy

Imagine a system with a parallel plate capacitor with holes in the middle where the plates are charged before being disconnected and insulated. Neutral atoms are introduced between the plates and are ...
symen schilstra's user avatar
-4 votes
1 answer
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Could a perpetual motion machine be made using a filling buoyant object that sinks when filled and releases when bottoming out? [duplicate]

Could you make a perpetual motion machine via buoyancy? If you started with 2 types of fluids with different buoyancy. Then add a buoyant object capable of filling with the top fluid where it closes ...
Jans Mcclain's user avatar
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3 answers
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Perpetuum mobile working in vacuum

Can a perpetuum mobile work in a vacuum? I think when it is in vacuum it won’t stop working because of outside forces, because there is no outside forces. Tell me if I’m wrong.
GeorgeBg4273's user avatar
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Can anyone explain me why this chain does not move? [closed]

Even, if this chain does not move then what will happen if the chain will move? can anyone elaborate "Epitaph of Stevinus" to me? I think it's applicable for all shapes of triangle until the ...
ayu's user avatar
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Can someone explain what did Feynman wanted to explain in his lectures (Vol 1, Chapter 4.2.)?

This is the text from Feynman lectures - Vol. 1 - Chapter 4-2 Gravitational potential energy: Consider weight-lifting machines—machines which have the property that they lift one weight by lowering ...
Calc_dude's user avatar
-7 votes
4 answers
394 views

Why wouldn't this perpetual motion machine work? [closed]

The water is supposed to run infinitely in this container, since when water drops the pressure inside the container decreases, which makes the water in the pipe ascend. I know that perpetual motion ...
Cosmic Dust's user avatar
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Perpetual motion in Nil-geometry?

By the Geometrization theorem, there are 8 "fundamental" geometries a 3D manifold can take-up (up to isomorphism). 5 of which ($R^3$, $H^3$, $S^3$, $S^2\times R$, and $H^2\times R$), I can ...
Graviton's user avatar
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Why doesn't this buoyant free energy device work?

Okay so I've seen a few of these but the setup here is a bit different. Suppose we set up an electrolysis plant at the bottom of the ocean and for some constant energy cost $E_1$, we can get a bunch ...
Kelvin's user avatar
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Why wouldn't this perpetual motion machine based on Archimede's principle work? [duplicate]

I found this today on the interwebs: Obviously this cannot work, but what bugs me is that I cannot figure out the part that would stop it and bring it to equilibrium. I suspect that it has to do ...
Vilx-'s user avatar
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Need help with solution on a physics calculation involving newtonian mechanics - (angular momentum) [closed]

I have been looking into conservation of energy in association with angular momentum (or in simple terms perpetual-motion-machines). Specifically need an answer to the following - Let's say there is a ...
Ravindra HV's user avatar
-2 votes
1 answer
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Yet another perpetual motion machine: does this imply large selective membranes are not possible? [closed]

So I was just thinking about the buoyant force and came up with what seemed like a simple perpetual motion based on it. Obviously such things are not physically possible so I'm trying to figure out ...
Sidharth Ghoshal's user avatar
1 vote
1 answer
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Is Newton’s third law of motion formed from Poincare symmetries?

So I know that Newton's third law states that every action has an equal reaction, making a symmetry. But just like how Poincare symmetries form conservation laws, do any Poincare symmetries form ...
Jungwoon Song's user avatar
-1 votes
4 answers
240 views

What would "break" in reality if I had a perpetual motion device? [closed]

Let's say aliens came and gave me a small box that outputs more energy than is input. As one example, the box can take current and voltage $I$ and $V$ as input, and output $I$ and $2\cdot V$. Or I can ...
chausies's user avatar
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Is this possible? [duplicate]

A picture that I found which boggles me . Is this possible? Will the vehicle move? I understand the answer is no cause than the oil companies will go bankrupt. But is there a physics explanation? Can ...
bibo999999's user avatar
-1 votes
1 answer
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Can someone explain why this would not create an infinitely rotating disk (perpetual motion) [closed]

This may be a dumb question and the solution may be super obvious but I can't figure it out as hard as I try. I have drawn a sketch of a device I thought of, now I know that we cant create "Free&...
Zincx II's user avatar
2 votes
2 answers
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Fake Perpetual Motion Device using an Electromagnet

I was watching a video of one of those fake perpetual motion machines where a ball falls down a hole and then flies off a ramp back onto the starting platform. As suspected, the large base is hiding ...
Tom's user avatar
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Why don't perpetual motion machines with superconducting magnets work?

A superconducting magnet works by energizing a superconducting magnetic coil, then short circuiting it to make a closed loop. Would it be possible to transfer the current back and forth between two ...
User850281's user avatar
0 votes
2 answers
104 views

Can heat generated by a falling object in a liquid be used as a perpetual motion machine?

I have a question regarding perpetual motion. I have tried to debunk it but I cant seem to find anything wrong with the concept. I think i am missing something so please help. There is a solid ...
sussyprisimbaka's user avatar
-2 votes
1 answer
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A Question What is wrong in my Gedankenexperiment? about the Conservation of energy [closed]

Please excuse my English... Let's say we have a 10m x 10m x 10m water tank filled with water. After a little search i found that the pressure on the sidings at 9-10m depth would be approximately -> ...
Strike AU's user avatar
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1 answer
724 views

Can magnets be used to create perpetual motion? [duplicate]

I have heard that magnets do not possess energy and can only help control it. Also, the first law of thermodynamics says that energy can neither be created nor be destroyed and hence making a ...
Sharath Prajith's user avatar
-1 votes
2 answers
304 views

Theory for a Perpetual Motion Machine based off of Electromagnetic Induction [closed]

So I was studying for a class and this idea suddenly struck me: A copper coil having around 3000 turns is wound around a wooden cylinder, forming a solenoid. A very powerful permanent magnet is taken (...
Akuno's user avatar
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2 answers
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How Newton's first law works in space?

If we have object in space and apply force over it. Does will the object continue his motion forever. When First law of Newton states: An object at rest remains at rest, and an object in motion ...
Deduce Uptight's user avatar
2 votes
1 answer
153 views

Question regarding reversible machines - Feynman Lectures Vol. I Chapter 4.2

In chapter 4.2 of the first Feynman Lecture, Feynman talks about deriving the formula for gravitational potential energy through facts and reasoning. He talked about weight-lifting machines, and ...
prado5083's user avatar
1 vote
0 answers
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How can i predict the amount of time it would take for my heron's fountain to stop? [closed]

I was assigned a project for my physics class and I'm supposed to build a Heron's fountain and to predict the time it would take to stop so I can then check it experimentally. However, I'm unsure of ...
andr.rods's user avatar
2 votes
2 answers
85 views

Would it be possible for someone, once flung, to continually orbit a small planetoid?

I am wondering this question (though it may seem obvious) because of an issue I'm having with a peer. He says that if a person is flung around a small planetoid, at just the right angle and velocity, ...
Clayton Hoxsey's user avatar
1 vote
2 answers
108 views

If light does not age and is timeless. Does it not contradict the principle of perpetual motion?

I read a previous question that asked if it is possible to date ancient light that has been emitted from a distant star. The best answer, explained that a photon does not ‘experience’ time as it is ...
Harvey's user avatar
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2 answers
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Is there a way to put a perpetual motion machine to work in space! [duplicate]

So I had this thought of a spinning disk that would spin forever in space then I imagined that on this disk there were magnets of alternating poles on the disk and then I imagined a bunch of copper ...
no name the astronaut's user avatar
1 vote
1 answer
499 views

Why this buoyancy machine won’t work? [duplicate]

(Check the video for a better understanding of the machine mechanism: https://www.youtube.com/watch?v=zIdn5zQTJAM&t=109s&ab_channel=RenewjouleLLC ) This machine has a different approach for ...
Ziad Eldoadoa's user avatar
-1 votes
1 answer
525 views

Why generating energy from the gravity side (air column) in a buoyancy chain machine isn’t possible? [duplicate]

(For simplicity let’s say that just 1 ball will be rotating into the machine.) It's proven that in a buoyancy chain machine the needed energy to submerge the ball into the water column will be (...
Ziad Eldoadoa's user avatar
0 votes
2 answers
285 views

Generator + Motor = Perpetual motion?

A DC generator work by converting the mechanical energy of the rotating coil to electrical energy and hence current is generated. What if this generated current is supplied to a motor which in turn ...
Booritth Balaji's user avatar
-5 votes
9 answers
7k views

Is it possible to generate electricity perpetually using only permanent magnets?

EDIT: I'm talking about generating electricity perpetually using only the magnets with no additional energy input. I'm sure the answer is no, but can you explain why it's not possible? Does it violate ...
228's user avatar
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1 answer
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Why Are Perpetual Motion Machines Defined As Not Having An External Energy Source? [closed]

Perpetual motion means motion that continues indefinitely if interpreted just by the meaning of the words. So why is the concept connected to having no energy source? Its not no-energy motion, its ...
Upsilon 17's user avatar
2 votes
2 answers
514 views

Why this perpetuum mobile won't work?

Design of this perpetuum mobile is based on brownian motion. When you place a small particle ($3\ \mathrm{\mu m}$) in liquid, you can see it moving randomly, because it gets hit by moving molecules. ...
Stanislav Goldenshluger's user avatar
-2 votes
1 answer
33 views

Energy calculation for second type perpetuum motion machine [closed]

How much energy would be obtained from the seawater with a second type perpetual motion machine if it were cooled by $\Delta T = 1° C$? The mass of the seawater is $m\approx1.4 \cdot 10^{21} \mathrm{...
Norman ray's user avatar
0 votes
2 answers
268 views

Why can't we generate electric current using thermal noise and diodes?

Would it be possible to generate electric current just by placing diodes in a circuit? All realistic circuits have some thermal noise (https://en.wikipedia.org/wiki/Johnson%E2%80%93Nyquist_noise). ...
Joseph Smith's user avatar
3 votes
3 answers
409 views

Where is this magnetic rail gun getting its energy?

Please watch this youtube video of a magnetic rail gun moving a marble. So as you already know, Conservation of Energy states that "energy can be neither created nor destroyed, but can only ...
burnt1ce's user avatar
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Why reverse osmosis does not cause perpetual motion?

In reverse osmosis, water molecules flow from dense solution to pure water under external pressure. But how does this process prevents perpetual motion? Consider the following example. Salt water ...
Kevin's user avatar
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2 votes
1 answer
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Can the Casimir effect propel this system?

Between two extremely close metal plates, there is a force of attraction because the metal plates have to be nodes of any electromagnetic quantum fluctuations and so there are less virtual particles ...
Myles_H's user avatar
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2 answers
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What prevents this infinite energy generator from working? [closed]

I thought up a device that uses the Oberth effect (wiki) to generate more energy than it consumes. Obviously, I made a mistake/logical error somewhere. Can you help me find it? Here's the thought ...
odin1337's user avatar
2 votes
1 answer
205 views

Would oil flow through a one-way valve into water by itself?

I read about heron's fountain recently and it got me thinking about liquid and air pressure and things like that. And it led me to the following idea: Basically what is happening here is that there ...
Quintonn's user avatar
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0 votes
1 answer
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My crazy superconductor idea

I watched a television documentary on superconductors. The summary was that in a ring of neodymium magnets, the superconductor would spin around on top of them levitating whilst it was frozen with ...
securityauditor's user avatar
0 votes
1 answer
83 views

Can gravity be utilized to generate hydropower in a clean, repeatable fashion without rivers or lakes? [closed]

I came up with this idea today and am just wondering if it is feasible. It is much easier to communicate via images so I drew the attached image to convey it. The key concept is rolling a ball in ...
user2708841's user avatar

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