Hot answers tagged perpetual-motion
42
The balls are entering the water well below the surface. The pressure there is much higher than at the surface. The work needed to push the balls into the water at this depth cancels the work gained when they float back up.
We can ignore the gravitational force on the balls since gravity pulls down as much as up as you traverse the loop.
Mathematically, ...
14
A simple symmetry argument might help here. Try to abstract everything away from your picture that is just a distraction. In the end it might look like this:
Why should this move to the left or to the right? It cannot and therefore adding a person and wheels does not change the problem.
12
The energy conservation law is compatible with every single observation we have made inside the Milky Way in science, or outside science, so the empirical evidence in favor of it is overwhelming, diverse, and universal.
Theoretically, the case is also clear. Emmy Noether demonstrated that conservation laws are linked to symmetries. The validity of the ...
10
Anything can rotate infinitely, if there is no friction. Rotating an object with constant velocity uses no energy to maintain. With friction it will loose energy and eventually stop. If you add a static magnetic field to the object, it will gain some finite potential energy, which in turn can be converted to kinetic energy.
Now if you add a changing ...
9
Thermodynamics does not prevent the trapping of heat. Here are limitations that thermodynamics does impose on the energy balance of the Earth:
The Earth's surface can not be (passively) warmed hotter than the temperature of the sun
The Earth's surface can not be (passively) cooled colder than the temperature of space
Those living on the Earth can not get ...
7
The problem is in the seal.
The amount of work to move the seal against the water pressure is the same amount of energy that is gained by the balls when they are pushed up by the water.
Even if we remove the seal and we imagine a magic "one-way pass-through" wall, the ball would still need to displace the same volume of water as itself in order to get into ...
6
A (non-accelerated) permanent magnet doesn't produce electromagnetic radiation. It is surrounded by a magnetic field (just like a charge is surrounded by an electric field), but it does not radiate. Especially there's no energy leaving the magnet.
Note that for energy flow (as in radiation) you need both an electric and magnetic field, because only then ...
5
First of all, nantennas in general don't violate the second law of thermodynamics, so they are not perpetual motion machines of second kind. As long as the total entropy goes up, the second law is obeyed. In other variables, it really means that a part of the incoming heat has to heat the nantenna up but there may still be a lot of energy left for energy ...
5
Coefficient of friction applicability
Saying the frictional force is $kMg$, opposite the direction of motion is a particular physical model. This model is not fundamental, and is certainly not 100% true, although it works pretty well for lots of practical situations. It applies for sliding between two surfaces, and it does not apply for a rolling ball.
...
5
If you need to produce the antimatter from (e.g. electric) energy – e.g. antiprotons may be produced from collisions of proton pairs at the LHC (most of the initial, "invested" energy is the kinetic energy of the protons there) – then you're obviously not getting an economic source of energy because you're converting energy to mass and back which would be ...
4
I'm afraid to say that unless we're considering incredibly cold superconductors (which have been known to sustain currents for years), none of these devices work. The first video offers instruction on building all manner of green devices including solar power generators and I'm not sure If it even claims to be a perpetual motion machine. I mention the other ...
4
It doesn't appear to be fraud (as suggested on Skeptics), but rather a good joke. The YouTube video ultimately links to this disclaimer for a great little website.
Apologies if I ruined the joke.
3
Actually, what is impossible is a perpetuum mobile which is a machine or system that breaks the first or second law of thermodynamics. Planetary motions break none of those laws, therefore there is no contradiction with their "perpetual motion".
The question of the end of Earth's orbit is a different one though. Certainly, the Earth's orbit will end, most ...
3
There is no reason why you couldn't build a motor using superconducting magnets, or build a simpler homopolar motor using a length of superconducting wire. There would be no heat dissipated due to electrical resistance, but of course there would still be mechanical resistance due to friction on the moving parts. The energy needed to overcome this, and to ...
2
Zassounotsukushi's answer is good, but I want to emphasize that there is a mistake here:
when I apply a force very very small in magnitude as compared to
KMg, then an equal amount of frictional force will be exerted by the
surface on the sphere at the point of contact.
The surface does not exert an equal force. The way friction works is that it ...
2
As others have said, a heat pump with an efficiency greater than unity doesn't have any problem with the laws of thermodynamics. There are still a few problems with this which mean that it isn't as good as it seems.
The efficiency of a heat pump depends on the temperature difference - you can get higher efficiencies when you're just increasing the ...
2
Yes, perpetual motion that does not work is possible, and has been done in a famous Soviet experiment. You put a superfluid in the interior of a macroscopic donut-shaped tube in the normal state, and let the tube spin along the donut axis, fluid plus pipe, then cool the thing down so that it becomes a superfluid. Then you stop the tube from spinning.
The ...
2
I guess the operative question here (no pun intended) is, what does it mean for a machine to "operate"? If you consider a particle that just sits there and doesn't do anything to be an operating machine, then yes, it is theoretically possible to build one. Just put an atom somewhere isolated and leave it there. In reality, of course, you can't do this ...
2
To answer the question you asked (which is possibly not what you meant to ask):
would the energy released by a matter-antimatter annihilation be more
than the energy needed to created the antimatter in the first place?
No, because that would give you a perpetual motion machine. If annihilation gave you more energy than it took to create the ...
2
Energy conservation in GR only holds approximately in spacetime regions that are very small, compared to curvature radii. But in general, since parallel transport is dependent on the trajectory in spacetime, an observer cannot uniquely define the energy of another distant observer.
The so-called Universal Time in the FLRW cosmology is a convention. We ...
2
You should read the question here energy conservation in general relativity to get a feel of the complexity of the problem.
You ask:
Why vacuum energy does not violate the principles of thermodynamic?
Thermodynamics is an emergent theory from classical statistical mechanics and that is based on quantum statistical mechanics. General relativity does ...
1
The Hawking radiation emitted from the Black Hole lowers its mass and reduces the energy in it's gravitational field. If you now drop the photographic plate back into the Black Hole you will get energy back. However if you take that energy away, by using it to generate electricity or whatever, you leave the Black Hole with a lower mass. That's where the ...
1
There is no such thing as real perpetual machine, as it defies the law of thermodynamics. Friction is definitely present as the ball goes around the track,and the air resistance force too. The magnets will slowly lose their magnetism over time and the ball will ultimately stop. Also, I do not see how ones can extract useful work from that machine.
1
The problem is that neither the potential energy nor the energy necessary to compress the gas is of any importance here. We can set the energy of the compression to zero and still would not gain any energy in this model! So for any real device with losses we certainly can't gain energy.
This can best be shown in an experiment by connecting a propeller to a ...
1
Your final sentence has the problem: "there must be some distance X that the device can rise than will generate more energy than what is needed by the compressor"
I think every attempt to prove this kind of thing has shown that there actually is not some distance which would meet these requirements.
1
I just read the paper today and here's my take, with several points still not really worked out, any help would be appreciated.
The last paragraph of the paper is extremely illuminating, I'm quoting it here (it should be fine right?):
In conclusion, a new regime for electroluminescent
cooling of a semiconductor diode was experimentally
demonstrated. ...
1
The left magnet is pulled forward, pulling the car behind it.
The right magnet is pulled backward, pushing the car ahead of it via the rod that attaches it to the car. (The fact that the rod loops over the car and attaches to the back makes no difference.)
If the rod is flexible, the car will move forward as the magnets move closer together, but only ...
1
The explanation is quite simple.
1) The big lever is used to "store energy"
2) When the pendulum is in the lowest point, the lever holding pendulum pivot will drop by height H, thus accepting mechanical energy equal to H x (F + G), where G is the weight of the pendulum (gravitational force = m x g) and F is the centrifugal force. If this drop occurs in the ...
1
Well that was an interesting waste of time. I'm trying to imagine poor Albert Einstein working in the patent office spending his time debunking stuff like:
hammering something against friction and saying "gee, it moved - that proves overunity"
rolling a cart against friction and saying "gosh it moved farther"
making a gadget with a pendulum, standing there ...
1
Can it run continously? No.
If you put it in a vacuum environment you will reduce losses due to the friction with air, but there are still other losses that will slow it down. For example friction in the bearings and eddy current losses.
It is possible though to store electricity in this way by converting it to rotational energy. Something similar is ...
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