Thread: Perpetual Motion Machine!!!! (well, not really)

I was reading up on Steorn, and it reminded me of an idea for a perpetual motion machine that I came up with when I was relatively young. My science teacher never took the time to explain why it wouldn't work, and a quick search for 'science forum' brought me here.

Wouldn't mind a little insight. :wink:



The eight blue rectangles represent permanent magnets - all of which have the same polarity. The inner four are attached to a flywheel. The outer four magnets are fixed in place, and partially obscured by the magnetic shields shown in red (which, I am assured, do exist). These are in place so that the magnets on the flywheel are only exposed to the magnetic field of the outer magnets once they are moving away from it. Since the magnets are of the same polarity, the wheel on the flywheel will be repelled, applying additional torque to the flywheel.

Now, I don't claim that this would work as I did come up with it when I was young and naive, but I still don't know why it wouldn't and wouldn't mind a little insight if someone would take the time?

Thanks.

your first problem (off the cuff) is friction on the axil - it will slowly sap your system of energy and thus grind it to a halt.

Couldn't he try using a very dense liquid that would stop the friction or a superfluid?

The real problem is of course you can't 'screen' the magnet so it repels!
IF it repels as it 'goes past' then it will as it 'gets to' so as you move it closer it will repel, if you move the other magnet so it comes near after the moving one has gone past then you need to inject energy to push both magnets. What you have described [ie repels as it goes past] is more like an electric motor [except that atracts as it comes towards then shuts off and the next magnet in line is energiesed] There is no way around it , you just can't beat the laws of conservation of energy this side of the big bang.

As a matter of interest there is no such thing as perpetual motion, even the universe is slowing down.