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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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&...
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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 ...
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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 ...
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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 ...
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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 -> ...
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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 ...
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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 (...
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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 ...
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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 ...
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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 ...
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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, ...
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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 ...
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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 ...
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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 ...
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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 (...
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Is Universe and everything inside in it is a perpetual motion machine? [duplicate]

The moon revolves around a planet. The planet revolves around a star, The whole galaxy is revolving around something unknown. All this is a continuous motion and only using the internal energy and ...
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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 ...
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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 ...
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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. ...
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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{...
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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). ...
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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 ...
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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 ...
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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 ...
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What prevents this infinite energy generator from working?

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 ...
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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 ...
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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 ...
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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 ...
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How does physics deal with perpetual motion in spins?

This is a bit a bit of a weird question. Simply put, if a body such as a planet spins, there is no internal issue (that I know of) that would cause it to eventually stop (by internal I mean that an ...
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How does physics deal with perpetual motion in orbits?

This is a bit a bit of a weird question. Simply put, if a body orbits something such as a black hole there is no internal issue (that I know of) that would cause it to eventually stop (by internal I ...
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Perpetual motion: Conditions for rolling a wheel sliding on a bar [closed]

This is a basic question about energy conservation and classical mechanics: Question: Under what situations can this motion be perpetual? Without gravity and without frictions. Without gravity and ...
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Is Thibado’s Graphene Brownian Capacitor Charger Perpetual Motion of the Second Kind?

In Fluctuation-induced current from freestanding graphene (peer-reviewed version on Phys. Rev. E, note: behind a paywall) Thiabado, et al, report the extraction of work from brownian motion. The ...
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Would it be possible to create a perpetual motion machine in an environment without air, friction, or dissipation?

Perpetual motion machines don't work because as it moves, the air molecules hit it and slow it down. Friction slows it down in a similar way. If there were no forces to slow it down, could it work?
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Perpetual motion machine with permanent magnets [duplicate]

I am not a physicist, but I know the first law of thermodynamic (conversation of energy), and I have connected this with an idea that came to my mind some time ago to create perpetual motion machine ...
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Perpetual machine from a PN-junction diode [duplicate]

Consider a PN junction diode Now, this system will naturally form a depletion region due to diffusion and will convert into this- Now, I wish to connect the ends of this diode with a conducting wire ...
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Feynman Lectures, Chapter 4, Fig 4-2

Chapter 4 of the Feynman Lectures Feynman defines the following: We imagine that there are two classes of machines, those that are not reversible, which includes all real machines, and those that are ...
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Eternal looping water tap

If i have a container like this (filled full with water): and I unplugged the small tap, would the water pressure be big enough to blast the water to the right side of the container and cause an ...
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What prevents a (theoretically ideal) railgun from being a perpetual motion device?

So, I understand the basics of how a railgun works - the current in the conducting rails and the armature sets up a magnetic field, which, via the Lorentz force acting on the current in the armature ...
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Buoyancy perpetual motion machine with compressors at top and decompress-or at bottom [closed]

a link to consideration about the perpetual motion machine [] diagrams and working out are included above. the assumptions are set to minimise engineering challenge and face perpetual motion machine ...
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'Perpetual motion' paper by George Biddell Airy

Airy wrote a paper (maybe deceptively) titled On certain Conditions under which a Perpetual Motion is possible (Cambridge Philosophical Transactions, December 14, 1829). Alternative site (in more than ...
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Perpetual Motions in atoms up scaled to Tesla

If perpetual motion exists in atoms or its parts then why can it not exist with a collection of atoms? or can it? What exactly prohibits or where does the perpetual line physically stop? Can atoms be ...
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Voltage drops in series - less work to do the same job

So I have been trying to explain electricity to younger siblings and it surprised me how little I know of what actually goes on. My question comes in the form of a consideration: Consider a ...
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2 votes
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A question about infinite energy

I know the conservation of energy doesn't allow that, and i saw a question on this forum about infinite energy: Why can't I do this to get infinite energy?, it says we can convert matter into ...
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Would electrons flow around the loop continuously in the following diagram

If there is a plate that is negatively charged (like the negatively charged plate of a capacitor) and it is brought near to (but not touching) a copper wire loop with a light bulb (load) and a diode (...
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The “free” energy device is possible if you look like this? [closed]

As I understood (please correct me if I am wrong) all “free energy” devices, in the end, stuck on the “energy conservation” law so you can’t have more energy than you put into the system. But I think ...
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A confusion about the impossibility of perpetual motion

It is stated that If any engine could produce a greater amount of work than that produced by a reversible cyclic heat engine, then it was possible to produce work endlessly by the following ...
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Do MRI scans take energy from the electro-magnet?

I read that a MRI machine generates a powerful magnetic field produced by an electric current. In order to get a high current (and a strong magnetic field) without too much heat as a side effect, ...
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Why would this evaporation-based perpetual motion machine not work?

This morning I was struck by an odd thought: Hydroelectric power stations get energy by dropping water from a height. The greater the height difference between top and bottom, the more energy can be ...
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Feynman's Reversible Machine Argument

In Feynman's Lectures on Physics, in the lecture on the conservation of energy, he makes the following argument: Consider weight-lifting machines—machines which have the property that they lift one ...
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Is "Air-gen" really possible, and how is it different from perpetual motion?

"Air-gen", as seen in Nature (See here and here), supposedly extracts net positive energy from ambient air at equilibrium. Is this really possible? Doesn't this violate a law of thermodynamics ...
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