Forget Oil - Contest: Find a substitute for oil.

CraigD · January 5, 2008

But I do believe it possible to build a machine which consumes only magnets (well the field generated by magnets) for fuel.

And of course when the magnets loose their magnetism they would have to be replaced so I guess it would litteraly consume magnets as well.

The problem with this approach is, as best I can tell, that demagnetizing a magnet – randomizing its constituent magnetic dipoles doesn’t produce energy, but consume it. Demagnetizing a magnet requires its many little dipoles to be twisted within its solid crystal matrix, which requires work/energy.

In principle, it should be possible to make an engine that takes, say, demagnetized iron, alnico, or a rare earth metal alloy, and generate energy as a by-product of magnetizing them.

Perhaps heating them to their Curie point, magnetize the material with a small magnetic field, then cool them, extracting more heat than was used to heat them?

Pretty complicated stuff, though, far beyond my skills of estimation or experimentation. :evil:

DFINITLYDISTRUBD · January 5, 2008

The problem with this approach is, as best I can tell, that demagnetizing a magnet – randomizing its constituent magnetic dipoles doesn’t produce energy, but consume it. Demagnetizing a magnet requires its many little dipoles to be twisted within its solid crystal matrix, which requires work/energy.

The Idea is not to deliberately demagnetise magnets but to use their force to produce sustainable motion untill the (as it seems) inevitable happens: they become too weak to continue to produce motion.

Of course some magnets have longer life spans than others. For example cheapy refrigerator magnets only last a couple of years whilst speaker magnets seem to remain strong for years. I've heard rare earth (neodimimium) magnets are suseptible to failure caused by excessive heat and strong magnetic fields (the latter seams kind of silly to me seeing as they have quite strong fields of their own.)

CraigD · January 6, 2008

The Idea is not to deliberately demagnetise magnets but to use their force to produce sustainable motion untill the (as it seems) inevitable happens: they become too weak to continue to produce motion.

I don’t think that can work. The problem is that you’re assuming a strong magnet has more potential energy than a weak one, which, as best I understand it, is exactly the opposite of the physical reality.

Consider what happens in a simple arrangement like this, 2 permanent magnets, one fixed, one on an axle, like this:

[math]

\unitlength 1mm

\begin{picture}(100,20)(0,0)

\put(0,15){\frame{\makebox(41,13)[lc]{N}}} \put(20,21.5){\circle{3}} \put(36,15){\makebox(5,13)[rc]{S}}

\put(45,15){\frame{\makebox(41,13)[lc]{N}}} \put(81,15){\makebox(5,13)[rc]{S}}

\end{picture}

[/math]

If 100% efficient (no frictional losses of any kind), set to rotating on its axle, this device would remain in motion indefinitely, neither gaining nor losing speed.

Each magnet is composed, essentially, of many small magnets, held in alignment, like this:

[math]

\unitlength 1mm

\begin{picture}(100,20)(0,0)

\put(0,15){\frame{\makebox(41,13){}}}

\put(1,16){\frame{\makebox(9,3)[lc]{n}}} \put(5,16){\makebox(5,3)[rc]{s}}

\put(11,16){\frame{\makebox(9,3)[lc]{n}}} \put(15,16){\makebox(5,3)[rc]{s}}

\put(21,16){\frame{\makebox(9,3)[lc]{n}}} \put(25,16){\makebox(5,3)[rc]{s}}

\put(31,16){\frame{\makebox(9,3)[lc]{n}}} \put(35,16){\makebox(5,3)[rc]{s}}

\put(6,20){\frame{\makebox(9,3)[lc]{n}}} \put(10,20){\makebox(5,3)[rc]{s}}

\put(16,20){\frame{\makebox(9,3)[lc]{n}}} \put(20,20){\makebox(5,3)[rc]{s}}

\put(26,20){\frame{\makebox(9,3)[lc]{n}}} \put(30,20){\makebox(5,3)[rc]{s}}

\put(1,24){\frame{\makebox(9,3)[lc]{n}}} \put(5,24){\makebox(5,3)[rc]{s}}

\put(11,24){\frame{\makebox(9,3)[lc]{n}}} \put(15,24){\makebox(5,3)[rc]{s}}

\put(21,24){\frame{\makebox(9,3)[lc]{n}}} \put(25,24){\makebox(5,3)[rc]{s}}

\put(31,24){\frame{\makebox(9,3)[lc]{n}}} \put(35,24){\makebox(5,3)[rc]{s}}

\end{picture}

[/math]

When a magnet looses strength (field flux), the many small magnets are rotated to no longer be as much in alignment, like this:

[math]

\unitlength 1mm

\begin{picture}(65,30)(0,0)

\put(0,15){\frame{\makebox(41,13){}}}

\put(1,16){\frame{\makebox(9,3)[lc]{n}}} \put(5,16){\makebox(5,3)[rc]{s}}

\put(11,16){\frame{\makebox(9,3)[lc]{s}}} \put(15,16){\makebox(5,3)[rc]{n}}

\put(21,16){\frame{\makebox(9,3)[lc]{n}}} \put(25,16){\makebox(5,3)[rc]{s}}

\put(31,16){\frame{\makebox(9,3)[lc]{n}}} \put(35,16){\makebox(5,3)[rc]{s}}

\put(6,20){\frame{\makebox(9,3)[lc]{n}}} \put(10,20){\makebox(5,3)[rc]{s}}

\put(16,20){\frame{\makebox(9,3)[lc]{n}}} \put(20,20){\makebox(5,3)[rc]{s}}

\put(26,20){\frame{\makebox(9,3)[lc]{s}}} \put(30,20){\makebox(5,3)[rc]{n}}

\put(1,24){\frame{\makebox(9,3)[lc]{n}}} \put(5,24){\makebox(5,3)[rc]{s}}

\put(11,24){\frame{\makebox(9,3)[lc]{s}}} \put(15,24){\makebox(5,3)[rc]{n}}

\put(21,24){\frame{\makebox(9,3)[lc]{s}}} \put(25,24){\makebox(5,3)[rc]{n}}

\put(31,24){\frame{\makebox(9,3)[lc]{n}}} \put(35,24){\makebox(5,3)[rc]{s}}

\end{picture}

[/math]

If you look at this last picture, you can see that it has a higher potential energy than the previous one. Rotating the little magnets to be misaligned – to have like poles facing one another – requires force applied over a distance, which is work. If this occurred because of magnetic and mechanical “jiggling” by the spinning device, the energy to do this work would have to have come from the kinetic energy of the spinning big magnet. So, even if all of the other mechanical parts are 100% efficient, the big magnet would lose speed and kinetic energy as the magnets lost strength, not gain it.

These are overly simplified drawing (the best I could manage using LaTeX :(). In reality, there would of course be many more little magnets, and they’d be at many angles, not always either exactly aligned or exactly reversed. Hopefully, they still communicate my points.

DFINITLYDISTRUBD · January 6, 2008

So, even if all of the other mechanical parts are 100% efficient, the big magnet would lose speed and kinetic energy as the magnets lost strength, not gain it.
-CraigD

Yeah...

The Idea is not to deliberately demagnetise magnets but to use their force to produce sustainable motion untill the (as it seems) inevitable happens: they become too weak to continue to produce motion.
- D.D.

Also your schematic is incorrect....the arrangement in the first picture would rotate exactly as far as necessary for "N" on the fixed magnet to be aligned to "S" on the rotating one. (unless you used a flywheel or something like that...but it would probably still grind to a halt in fairly short order.)

Thinking bout it here it seems to me that another fixed magnet on the left side of the rotor aligned "S"-"N"* would allow this arrangement to go for a fair amount with a flywheel assisting.

*yielding "S"-"N" "A"-"B" "Y"-"Z"

"S"= south pole left fixed magnet "N"= north pole left fixed magnet

"A"=north pole rotating magnet "B"=south pole rotating magnet

"Y"=north pole right fixed magnet "Z"=south pole right fixed magnet

Like poles repell, opposite poles attract...that said the above layout should yield two push pulls per revolution.

DFINITLYDISTRUBD · January 6, 2008

It seems to me that you still think I'm shooting for perpetual motion. :fire:

Yes the magnets will lose energy over time (weaken).:eek:

Yes the machine will slow down and stop eventually (due to the magnets weakening which is why I mentioned that it would need new ones in previous posts above):(

I don’t think that can work. The problem is that you’re assuming a strong magnet has more potential energy than a weak one, which, as best I understand it, is exactly the opposite of the physical reality.
-CraigD

You lost me....right here.....uh...sure.....o.k....kindly tell that to the magnets that keep falling off my fridge...While you're at it DON'T tell my shop's saftey officer or it's owner!!!!! The last thing I need is 5 tons of steel traveling overhead held up by weak lifting magnets!!!!!! :hyper:

Don't get me wrong but that one makes exactly no sence to me...of course I'm of the "get a bigger hammer" school of thought!:camera:

CraigD · January 6, 2008

It seems to me that you still think I'm shooting for perpetual motion.

I think I understand your basic idea, the use of permanent magnets as a sort of “fuel”. There’s nothing “perpetual motion-y” about this. As long as energy is being extracted from the magnet, it can at least in principle be used to do physical work – in other words, to power a motor.

The problem, as I see it, is that, like many others I’ve seen propose such a motor, you have the physics of a magnet exactly backwards. You’re assuming (perhaps because they’re more useful in devices like refrigerator magnets and electric motors?) that, a strong magnet contains more energy than a weak one. This is simply incorrect.

Consider the following very simple arrangement:

#1: [math]

\unitlength 1mm

\begin{picture}(65,30)(0,0)

\put(6,20){\frame{\makebox(9,3)[lc]{n}}} \put(10,20){\makebox(5,3)[rc]{s}}

\put(16,20){\frame{\makebox(9,3)[lc]{n}}}

\put(20.5,21.5){\circle{1}}

\put(20,20){\makebox(5,3)[rc]{s}}

\put(26,20){\frame{\makebox(9,3)[lc]{n}}} \put(30,20){\makebox(5,3)[rc]{s}}

\end{picture}

[/math]

#2: [math]

\unitlength 1mm

\begin{picture}(65,30)(0,0)

\put(6,20){\frame{\makebox(9,3)[lc]{n}}} \put(10,20){\makebox(5,3)[rc]{s}}

\put(16,20){\frame{\makebox(9,3)[lc]{s}}}

\put(20.5,21.5){\circle{1}}

\put(20,20){\makebox(5,3)[rc]{n}}

\put(26,20){\frame{\makebox(9,3)[lc]{n}}} \put(30,20){\makebox(5,3)[rc]{s}}

\end{picture}

[/math]

where the [math]

\unitlength 1mm

\put(20,21.5){\circle{1}}

[/math] is a axle.

It should be clear that #2 contains more usable energy than #1. Attach a transmission to its axle, and as the middle magnet rotates so that it matches arrangement #1, force and work (AKA energy) can be had from it. Attach a transmission to #1, and nothing happens, no force, on work.

Now, consider the simplified pictures of a strong and a weakened magnet in post #20:

Strong magnet: [math]