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Perpetual Motion by Robert Nemiroff Michigan Technological University.

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Presentation on theme: "Perpetual Motion by Robert Nemiroff Michigan Technological University."— Presentation transcript:

1 Perpetual Motion by Robert Nemiroff Michigan Technological University

2 Physics X: About This Course Officially "Extraordinary Concepts in Physics" Being taught for credit at Michigan Tech o Light on math, heavy on concepts o Anyone anywhere is welcome No textbook required o Wikipedia, web links, and lectures only o Find all the lectures with Google at: "Starship Asterisk" then "Physics X" o

3 Perpetual Motion is... technically, something that is always in motion. practically, a machine that generates energy from nothing. However, Newton's law indicates that anything that starts in motion, remains in motion, so in this sense perpetual motion is expected. Machines that generate energy from nothing have never been found and are now considered a waste of time.

4 Perpetual MotionPerpetual Motion Machine: First Kind Perpetual motion machines of the first kind generate energy from nothing. This violates the local conservation of energy, and since this energy can be used to generate heat or work, it also violates the first law of thermodynamics:first law of thermodynamics 1st Law: "The change in the internal energy of a system is equal to the amount of energy added by heating the system minus the amount lost as a result of the work done by the system on its surroundings."

5 Perpetual MotionPerpetual Motion Machine: Second Kind This type of perpetual motion machine uses heat as a power source directly and continuously, without the flow of heat to a sink. This violates the second law of thermodynamics.second law of thermodynamics 2nd Law: "Heat (macroscopically) cannot flow spontaneously from a material at lower temperature to a material at higher temperature."

6 Perpetual MotionPerpetual Motion Machine: Third Kind This type of perpetual motion machine relies on eliminating friction. Technically, this is not so much an energy generating machine so much as an energy storage device. It is not possible to move with zero friction, so although low friction devices are real, zero friction devices are not.

7 Perpetual MotionPerpetual Motion Machine: Useful Thought Experiments At least two classic though experiments seem to create perpetual motion machines. Maxwell's Demon (analyzed in another lecture) Brownian Rachet Wheel

8 Perpetual MotionPerpetual Motion: Brownian Ratchet Wheel Brownian Ratchet Wheel

9 Perpetual MotionPerpetual Motion: Brownian Ratchet Wheel Brownian Ratchet Wheel A ratchet wheel with cogs has a paw that allows it only to rotate in one direction. Random brownian motion of the air molecules strike the wheel, sometimes causing enough motion so that it clicks forward one cog. The paw prevents it from even clicking back. Is the slow rotation of the wheel perpetual motion? 1. Yes, you've done it! 2. No. 3. It depends in how many dimensions the paw can move.

10 Perpetual MotionPerpetual Motion: Brownian Ratchet Wheel Brownian Ratchet Wheel No. The wheel will only rotate as expected when the the ratchet and paw are significantly colder than the surrounding air or the heat bath. Then the device works by tapping into the heat flowing from the heat bath to the wheel. When everything is the same temperature, the paw may have its own Brownian motion and will allow the wheel to go in either direction.

11 Perpetual Motion: Magnetic Tower Magnetic Tower Balls are pulled up a ramp by a powerful permanent magnet but then drop through a hole at the top, returning them to their original position.

12 Perpetual Motion: Magnetic TowerMagnetic Tower Why doesn't this work? 1. Any magnet powerful enough to pull the balls up the ramp would be powerful enough to keep them from dropping through the hole. 2. The rolling ball would at first be attracted to the magnet, but after it rolled its polarity would reverse and it would then be repelled from the magnet. 3. The system works, but there is no way to extract power. 4. The electric companies kill anyone who gets too close to making this work to protect the profit of their investors.

13 Perpetual Motion: Magnetic TowerMagnetic Tower Why it doesn't work: 1. Any magnet powerful enough to pull the balls up the ramp would be powerful enough to keep them from dropping through the hole.

14 Perpetual Motion: Float BeltFloat Belt Hollow balls float up through water, only to be pulled back down as they descend in air.

15 Perpetual Motion: Float BeltFloat Belt Why doesn't this work? 1. There is no way to push the balls in at the bottom without losing water. 2. Pushing the balls in at the bottom will take at least as much energy as gained from the balls floating up and the falling down. 3. This will work only so long as the water is cooler than the ping pong balls. 4. A team at Brookhaven is now nearing break-even energy for device that works on the same principle.

16 Perpetual Motion: Float BeltFloat Belt Why it doesn't work: 2. Pushing the balls in at the bottom will take at least as much energy as gained from the balls floating up and the falling down.

17 Perpetual Motion: Conservative Forces Conservative Forces A conservative force creates work on a particle that is independent of the path taken. Therefore, paths that return to their starting point can gain no work -- no energy. Therefore, a conservative force field cannot be used to create a perpetual motion machine that generates energy. Examples of conservative force field include Newtonian gravitational force and Coulomb electric force.

18 Perpetual Motion Machines: The US Patent Office The US Patent Office Many people try to patent their own perpetual motion machines. The US Patent office will no longer grant patents to machines that it feels are perpetual motion power generators, without a working model. Some people try to create machines so complex that no one could determine their efficiency without such a model.

19 Perpetual Motion Machines: Complex Hoaxes Examples: Machines that are powered by a cleverly hidden person. Motion_Machine_of_Charles_Redheffer/

20 Perpetual Motion Machines: RJN Advice If you have created a true perpetual motion machine from which you create free energy, please do not hold press conferences and tell everyone. Please start creating power from your machine and selling it. The electric company MUST buy it, and you can make a fortune.


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