Perpetual motion

There are many equivalent statements of the second law, some of which involve statements about heat engines and perpetual motion machines of the second kind that appear superficially quite different from equation (A2.T21). They will not be dealt with here, but two variant fonns of equation (A2.T21) may be noted in... 

In free molecular flow, if gaseous conductance were not independent of the flow direction, a perpetual-motion machine could be constmcted by connecting two large volumes by a pair of identical ducts having a turbine in front of one of the ducts. A duct that has asymmetricaUy shaped grooves on its waU surface could alter the probabUity of molecular passage in such a way that for a tube of equal entrance and exit areas, the probabUity of passage would be made directional. 

When heat is transformed into any other form of energy, or when other forms of energy are transformed into heat, the total amount of energy (heat plus other forms) in the system is constant. This is known as the first law of thermodynamics, i.e., the eonservation of energy. To express it another way it is m no way possible either by meehanieal, thermal, ehemical, or other means, to obtain a perpetual motion maehine i.e., one that ereates its own energy. 

Thermodynamic considerations demand that the energy necessary for biosynthesis of any substance exceed the energy available from its catabolism. Otherwise, organisms could achieve the status of perpetual motion machines A few molecules of substrate whose catabolism yielded more ATP than required for its resynthesis would allow the cell to cycle this substance and harvest an endless supply of energy. 

John W. Keely (lS27-1898j sealed to what he claimed was Ihe first perpetual motion machine until after he died. (Corbis Corporation)... 

To prove that a particular design of a perpetual motion machine will not work can be vei y time consuming, and the predictable negative result has never been worth the effort. Therefore, the U.S. Patent Office has a policy to not examine applications covering perpetual motion machines unless the applicant furnishes a working model. 

The nonexistence of perpetual motion machines, despite centuries of effort to design them, has been used to support the law of consciwation of energy. This law is based, however, not on this negative result, but on all the experiments performed to date in which energy is carefully accounted for. It has never been observed to fail. This law is, therefore, a good basis from which to analyze perpetual motion machines. It clearly states that the goal of getting... 

There are many systems in nature that for practical purposes are perpetual. The rotation of the Earth does not change perceptibly in any person s lifetime. Very careful measurements can detect such changes, and they arc predictable based on the tidal interaction with the sun and the moon. At the current rate of decrease, the Earth s rotation relative to the Sun would stop in 5.4 billion years. Systems that are unchanging lor practical purposes, but which are running down ever so slowly, do not count as perpetual motion. 

The electrons of atoms in their ground state are in perpetual motion. Also, in a gas, each atom has an average kinetic energy (motion) depending on the temperature of the gas. These motions don t count ei th er because humans demand something on their own scale that they can see or take advantage of before they consider it as true perpetual motion. 

The consideration of the simple pendulum illustrates the basic problem behind devising a perpetual motion machine. The problem is the fact that energy exists in several forms and is transformed from one form to the other, especially when motion is involved. Even if friction is eliminated, there arc still the electromagnetic radiation and gravitational inter-... 

There would remain some very small residual motion of the pendulum due to the air molecules striking it at random (Brownian motion), but that does not count in the game of perpetual motion. In the condition of residual motion, the pendulum is just another (big) molecule sharing equally in the average kinetic energy of all the individual air molecules. In other words, the pendulum eventually comes to thermal equilibrium with the air. 

Similar considerations apply to all other schemes to produce perpetual motion. No matter how it is designed, an isolated system will always tend toward a condition of thermal equilibrium, which never involves motion of objects on a human scale, and is thus not perpetual motion. ... 

Ord-Hume, A. (1977). Perpetual Motion The History of an Obsession. New York St. Manin s Press. 

Their data translated into a power output of lOOW/kg. Where was the power coming from Was this finally an illimitable source of energy, nature s own perpetual-motion machine It was here that Einstein, in a concise phrase, carried the argument to its limit. In his own derivation of = mcr in 1905, five years after Poincare s observation, he remarked that any body emitting radiation should lose weight. 

George earned the prestigious position of brakesman at the Dolly Pit colliery, responsible for the engine used for hauling coal out of the mines. He was married in 1802. During that year he made an unsuccessful attempt to build a perpetual motion machine. But he did gain respect in the community as an accomplished clock-mender. 

Viewing things from the perspective of his physical theory of contact electricity, Volta was intrigued by the apparently endless power of the battery to keep the electric fluid in motion without the mechanical actions needed to operate the classical, friction, electrostatic machine, and the electrophorus. He called his batteiy alternately the artificial electric organ, in homage to the torpedo fish that had supplied the idea, and the electromotive apparatus, alluding to the perpetual motion (his words) of the electric fluid achieved by the machine. To explain that motion Volta relied, rather than on the concepts of energy available around 1800, on his own notion of electric tension. He occasionally defined tension as the effort each point of an electrified body makes to get rid of its electricity but above all he confidently and consistently measured it with the electrometer. 

South Dakota School of Mines and Technology Mechanical Transmission of Energy Perpetual Motion Propulsion... 

The whole process now commences anew, and the result is a never-ending circulation of matter round the tube, i.e., a perpetual motion, which is impossible. Hence the partial pressures of both components are equal over a and ft, and therefore also is their sum, i.e., the total vapour pressure. 

The predictions of the Third Law have been verified in a sufficiently large number of cases that experimental attempts to reach absolute zero are now placed in the same class as attempts to devise perpetual motion machines — which is to say there are much more productive ways to spend one s time. Much experimental work is carried out. however, at very low temperatures, because the behavior of matter under these conditions has produced many surprises and led to the uncovering of a great deal of new knowledge and the development of useful new devices, such as superconducting magnets.cc... 

European Plastics News 24, No. 8, Sept. 1997, p.37 PERPETUAL MOTION... 

This is a very simple example of apparent constant flow of planets round the Sun. It can be treated as close to perpetual motion with no material changes. We describe the system first before we explain why it is a simple but not a quite correct case. The planets flow in orbits under two forces or fields - gravity and centrifugal force . The velocity is assumed to be fixed. Hence the systems have form, structure , which is constantly repeated, but no information passes between the objects as everything in the system is part of the form and without any of the pieces, planet masses, the Sun and gravitational forces, there would be no flow. The total of all the parts is needed to maintain the flow characteristics of the formed whole system. It is clear that the system is not to be described as random and it has an evolutionary cause even though generated by accident, and has allowed life. 

The rationale is like settling the issue around perpetual motion machines by the second law of thermodynamics rather than examine each proposed device independently. 

Iod—To know the laws of perpetual motion and to prove quadrature of the Circle. 

Claims of perpetual motion create moments of mirth and consternation for those knowledgeable in the laws of thermodynamics. Yet, is it only hyperbole when a responsible journal such as the European Plastics News [1] proclaims that depolymerization of polyethylene terephthalate (PET) can be repeated indefinitely The second law of thermodynamics brings us back to reality. The depolymerization of PET does not operate at 100% yields, but does offer the opportunity for near-stoichiometric recovery of the monomers used to make the polyester. With high yields of potentially valuable monomers, the commercial potential for polyester depolymerization to regain feedstocks must be considered. 

Perpetual motion machines seem to be a favourite project for inventors who do not understand the second law of thermodynamics. Design a simple machine that, once started, would recycle energy and, according to the first law of thermodynamics, should carry on forever. Why does the second law of thermodynamics rule out the possibility of ever making a perpetual motion machine ... 

If such a machine could be constmcted, it would be a perpetual-motion machine of the second kind. ... 

First Law of Thermodynamics. The total amount of energy within a closed system is constant (/.e., the total energy of the system is conserved). Mathematically, this can be expressed as AU = q + w where At/ is the change in internal energy, q is the heat transferred to the system, and w is the work done on the system (or, dU = dq + dvr). Internal energy is a state function (/.c., it is dependent only on the initial and final states and not on the path between those states). In addition, the validity of the first law means that perpetual motion machines are impossible. See Conservation of Energy... 

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