Monday, August 5, 2013

Magnetic Perpetuum Mobile

Is this a Magnetic Perpetuum Mobile?

The law of conservation of energy forbids perpetual motion. On the other hand, the small magnets in this image seem to be attracted / repelled by the large magnet, producing motion. As a child, I imagined this machine, and for a while I was perplexed, since on the one hand I knew it can't move forever, because it would break conservation of energy, but on the other hand, it is not that obvious what exactly happens that makes it stop.


Elie Nasrallah said...

Very good paradox but the explanation is too concise.

Cristi Stoica said...

Thanks. It is indeed concise. I posted a slightly longer explanation at Physics Stack Exchange.