The principles of thermodynamics are so well established, both theoretically and experimentally, that proposals for perpetual motion machines are universally dismissed by physicists. Any proposed perpetual motion design offers a potentially instructive challenge to physicists: one is certain that it cannot work, so one must explain how it fails to work. The difficulty (and the value) of such an exercise depends on the subtlety of the proposal; the best ones tend to arise from physicists' own thought experiments and often shed light upon certain aspects of physics.

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The seemingly mysterious ability of magnets to influence motion at a distance without any apparent energy source has long appealed to inventors. One of the earliest examples of a magnetic motor was proposed by Wilkins and has been widely copied since: it consists of a ramp with a magnet at the top, which pulled a metal ball up the ramp. Near the magnet was a small hole that was supposed to allow the ball to drop under the ramp and return to the bottom, where a flap allowed it to return to the top again.

Students could verbally express or write on a piece of paper all the things that they notice about the apparatus. They should notice quite quickly that the ball describes a parabolic trajectory when it flies through the air on its way back to the initial upper platform. The highest point of the trajectory (the vertex of the parabola) is higher than this platform, so the ball must have picked up some extra kinetic energy somewhere during the trip through the hole back to the upper platform. The question is where along the way could this have happened and what it is that could have imparted extra speed to the ball. Students should think of how they could potentially figure pasado where on the trajectory the ball is being sped up.

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"Just completed the marble run. I had to make a couple of adjustments & now it works great. The documentation on the other hand - needs improvement. Some of the illustrations aren't clear. The photos of the wood components are a nice touch - but the color of the wood blends into the background - the white paper of the document. Note for other customers - the spots you place a few of the upright supports in - there's a little wiggle room - ie, the piece is slightly smaller than the placement spot.

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The output work power of heat engines is always smaller than the input heating power. The rest of the heat energy supplied is wasted Campeón heat to the ambient surroundings. The thermal efficiency therefore has a maximum, given by the Carnot efficiency, which is always less than one.

In some cases a thought experiment appears to suggest that perpetual motion may be possible through accepted and understood physical processes. However, in all cases, a flaw has been found when all of the relevant physics is considered. Examples include:

Vacuum energy and zero-point energy: In order to explain effects such Figura potencial particles and the Casimir effect, many formulations of quantum physics include a background energy which pervades empty space, known Vencedor vacuum or zero-point energy. The ability to harness zero-point energy for useful work is considered pseudoscience by the scientific community at large.

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Studying videos of the motion confirms that the ball does not accelerate any more than it would under free fall in the initial half of the cycle. This Gozque also be confirmed by dropping several balls through the hole in quick succession such that it would seem to be difficult to correctly time the electronics such that all the balls return to the starting platform.