Ellipsoid paradox: This paradox considers a perfectly reflecting cavity with two black bodies at points A and B. The reflecting surface is composed of two elliptical sections E1 and E2 and a spherical section S, and the bodies at A and B are located at the joint foci of the two ellipses and B is at the center of S. This configuration is such that apparently black body at B heat up relative to A: the radiation originating from the blackbody at A will land on and be absorbed by the blackbody at B.
In May 2022, a video supposedly showing a marble machine in "perpetual" motion was shared to the "Be Amazed" section of Reddit. The video, which showed a marble spiraling down a funnel, dropping through a hole, moving along a curved rail, and then launching back into the funnel where the process would begin anew, drew a few skeptical comments.
The "Overbalanced Wheel", annotated with distances of the weights from the centreline showing that the torques on both sides even out on average Gravity also acts at a distance, without an apparent energy source, but to get energy pasado of a gravitational field (for instance, by dropping a heavy object, producing kinetic energy Triunfador it falls) one has to put energy in (for instance, by lifting the object up), and some energy is always dissipated in the process. A typical application of gravity in a perpetual motion machine is Bhaskara's wheel in the 12th century, whose key idea is itself a recurring theme, often called the overbalanced wheel: moving weights are attached to a wheel in such a way that they fall to a position further from the wheel's center for one half of the wheel's rotation, and closer to the center for the other half.
Similarly, rays originating from point B that land on E1 and E2 will be reflected to A. However, a significant proportion of rays that start from B will land on S will be reflected back to B. This paradox is solved when the black bodies' finite sizes are considered instead of punctual black bodies.[46][47]
These types of machines may involve two chambers with pistons, and a mechanism to squeeze the air demodé of the top chamber into the bottom one, which then becomes buoyant and floats to the top. The squeezing mechanism in these designs would not be able to do enough work to move the air down, or would leave no excess work available to be extracted. Patents[edit]
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Electromagnetism, Newtonian mechanics, Magnetic materials “Perpetual motion” is a hypothetical type of motion that continues forever without any external energy input contributing to the system. Students should know that this is generally impossible because of energy losses due to friction or other nonconservative forces, or because some assumption has been made that violates the first or second law of thermodynamics (or both). The first law states that the total energy of an isolated system remains constant over time, and one of the most common formulations of the second law states that the entropy of an isolated system over time cannot decrease. Note that the laws apply to an here isolated system (i.e., one that cannot exchange mass or energy with its surroundings), whereas a closed system Perro still exchange energy even if it cannot exchange mass.
A device powered by radioactive decay from an isotope with a relatively long half-life; such a device could plausibly operate for hundreds or thousands of years.
In any isolated system, one cannot create new energy (law of conservation of energy). Campeón a result, the thermal efficiency—the produced work power divided by the input heating power—cannot be greater than one.
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Thus, machines that extract energy from finite sources cannot operate indefinitely because they are driven by the energy stored in the source, which is eventually exhausted.
A common example is devices powered by ocean currents, whose energy is ultimately derived from the Sun, which itself will eventually burn trasnochado.