Why Can't Permanent Magnets Create a Perpetual Motion Machine?

[elliswonders]

Hey all, I'm hoping you can help me out on this. First, I should mention that I'm not one of those folks who believes in "free energy." I submit to the law of energy conservation, but recently I've been trying to figure out why a perpetual motion machine made of permanent magnets wouldn't work. Here's a reference of sorts:

Now, I get that I'm missing something, but could I get a clear explanation of why that thing isn't really spinning on its own? (And please be nice. I KNOW I don't know as much as some people here, that's why I'm asking in the first place).

On a related note, even if a machine similar to the one in the link isn't creating "free energy," would it be possible to build one that lasts a long time? Why wouldn't that be a viable alternative to current energy sources? I'm not looking to run out and try this myself, I'm here to learn!

Thanks in advance!

 

[ModusPwnd]

Im not a moderator, but I suspect this thread will be locked. PhysicsForums doesn't generally do "debunking" in this fashion for a variety of reasons.

 

[Drakkith]

Modus is correct. Discussion of perpetual motion machines, free energy devices, and similar trains of thought are not allowed here at PF, not even for the purposes of debunking them. That kind of discussion is a magnet for crackpots, as past experience has shown us.

If you wish to understand why these machines don't work, your best bet is to learn about magnets and how they work.

 

[elliswonders]

I guess I can appreciate that policy. And I guess I'd gain more in the long run if I figured this one out for myself (as I already KNOW the answer...but just like a physics test question, answers aren't worth nill if you can't show your work...)

Also, nice pun Drakkith :D

 

[berkeman]

Thread closed.

Please check out the links in the PF Rules concerning our banned topics -- they should help you to answer your questions

Pseudoscience, such as (but not limited to):

Perpetual motion and "free energy" discussions
http://wiki.4hv.org/index.php/Free_Energy_Debunking
http://en.wikipedia.org/wiki/Perpetual_motion
http://www.skepdic.com/freeenergy.html
http://www.skepdic.com/perpetual.html