از شما عاجزانه تقاضا دارم این متن انگلیسی را برایم ترجمه کنیدمن یک مخترع هستم که به این مقاله نیاز حیاتی دارمشما با ترجمه این متن هم در ترجمه انگلیسی روان تر میشوید و هم به علم کمک بزرگی میکنیدممنون
The seemingly mysterious ability of magnets to influence motion at a distance without any apparent energy source has long appealed to inventors. Unfortunately, a constant magnetic field does not do work because the force it exerts on any particle is always at right angles to its motion; a changing field can do work, but requires energy to sustain. A "fixed" magnet can do work, but energy is dissipated in the process, typically weakening the magnet's strength over time. Thus, when a magnet does work by lifting an iron weight, potential energy is converted to kinetic energy. Once the iron hits the magnet its kinetic energy is converted to heat and sound. In order to release further energy, the iron must be moved away from the magnet. This converts the energy of your arm to potential energy again. Since the energy of parting the magnet and iron is identical to the energy released as the magnet and iron come together, no net energy can be gained by changing the iron - magnet distance. Gravity also acts at a distance, without an apparent energy source. But to get energy out of a gravitational field (for instance, by dropping a heavy object, producing kinetic energy as it falls) you have 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, 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. Since weights further from the center apply a greater torque, the result is (or would be, if such a device worked) that the wheel rotates forever. The moving weights may be hammers on pivoted arms, or rolling balls, or mercury in tubes; the principle is the same. Gravity and magnetism are an attractive combination indeed, and a frequently rediscovered design has a ball pulled up by a magnetic field and then rolling down under the influence of gravity, in a cycle. (At the highest point, the ball is supposed to have acquired enough speed to escape the magnet's influence.) To extract work from heat, thus producing a perpetual motion machine of the second kind, the most common approach (dating back at least to Maxwell's demon) is unidirectionality. Only molecules moving fast enough and in the right direction are allowed through the demon's trap door. In a Brownian ratchet, forces tending to turn the ratchet one way are able to do so while forces in the other direction aren't. A diode in a heat bath allows through currents in one direction and not the other. These schemes typically fail in two ways: either maintaining the unidirectionality costs energy (Maxwell's demon needs light to look at all those particles and see what they're doing), or the unidirectionality is an illusion and occasional big violations make up for the frequent small non-violations (the Brownian ratchet will be subject to internal Brownian forces and therefore will sometimes turn the wrong way).The recorded history of perpetual motion machines dates at least as far back as the 8th century. Proponents of perpetual motion machines use a number of other terms to describe their inventions, including "free energy" and "over unity" machines. An early description of a perpetual motion machine was by Bhaskara in 1150. He described a wheel that he claimed would run forever. Villard de Honnecourt in 1235 described, in a thirty-three page manuscript, a perpetual motion machine of the second kind. In 1775 Royal Academy of Sciences in Paris issued the statement that Academy "will no longer accept or deal with proposals concerning perpetual motion". Johann Bessler (also known as Orffyreus) created a series of claimed perpetual motion machines in the 18th Century. In the 19th century, the invention of perpetual motion machines became an obsession for many scientists. Many machines were designed based on electricity, but none of them lived up to their promises. Another early prospector in this field included John Gamgee. Gamgee developed the Zeromotor, a perpetual motion machine of the second kind. Devising these machines is a favourite pastime of many eccentrics, who often come up with elaborate machines in the style of Rube Goldberg or Heath Robinson. These designs may appear to work on paper at first glance. Usually, though, various flaws or obfuscated external power sources have been incorporated into the machine. Such activity has made them useless in the practice of "invention".
توجه
نوشته شده توسط abbas13677_2005
سلام ترجمه لطفا
