Perpetual Motion

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
• Light on math, heavy on concepts
• Anyone anywhere is welcome
• No textbook required
• Wikipedia, web links, and lectures only
• Find all the lectures with Google at
• "Starship Asterisk" then "Physics X" 
• http//bb.nightskylive.net/asterisk/viewforum.php?
  f39

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 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
• 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 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.
• 2nd Law "Heat (macroscopically) cannot flow
  spontaneously from a material at lower
  temperature to a material at higher temperature."

6
Perpetual 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 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 Motion Brownian Ratchet Wheel

•  

9
Perpetual Motion 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 Motion 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

• 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 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 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 Belt

• Hollow balls float up through water, only to be
  pulled back down as they descend in air.

15
Perpetual Motion Float 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 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 MotionConservative 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 MachinesThe 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. 
• http//www.museumofhoaxes.com/hoax/Hoaxipedia/Perp
  etual_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.