energy

[andymadmak]

I understand that new energy cannot be created, it can only be converted from another form of energy. That being the case, what energy is being converted when the two magnets on my desk pull themselves together? The kinetic enrgy displayed must have been converted from something? Confused

[hairykrishna]

There's potential energy stored in the system due to the positioning of the magnets. It's easier to understand if you think about 'resetting' the system after the magnets are stuck together. You need to put in some work to separate the magnets back to their starting positions.

[stew-S160]

Potential energy(magnetic force) being converted into kinetic energy(magnets moving towards each other).
(assuming no friction.)

[andymadmak]

OK, I think I get it. But, does this mean that if you kept sticking things to the magent and pulling them away again it would eventually run out of magnetic power? (on the basis that no energy conversion is 100% efficient)

[hairykrishna]

No, not to any significant degree. All the magnet is doing is providing a force, sticking stuff to it and moving it away again won't deplete it. Think about an electric motor, one which includes permanent magnets, that's essentially the same as sticking and removing stuff thousands of times a second.

[Simpo Two]

What we need is magnets that can be retuned so they pick up any material...

[hairykrishna]

Well, everything is magnetic for a given value of 'magnetic' because of diamagnetism. See the levitating frog;

http://www.youtube.com/watch?v=A1vyB-O5i6E

You just need a really strong magnet!

[stew-S160]

The only way to reduce or 'turn off' a magnetic effect, is to change the polarity of the atoms.


It would be 'super cool' if we could use Mag Lev for most things in every day life.

[Mave]

From an energy conservation point of view, it's no different to gravitational bodies. Pulling magnets apart from each other is similar to lifting something from the floor. Letting the magnets bash together is the same as dropping something...

[R300will]

andymadmak said:

I understand that new energy cannot be created, it can only be converted from another form of energy. That being the case, what energy is being converted when the two magnets on my desk pull themselves together? The kinetic enrgy displayed must have been converted from something? Confused

The energy would be converted into kinetic energy as they slid together, sound, heat from friction of the table. The magnets would also be very very very slightly lighter as well due to the energy loss.

[Williams99]

stew-S160 said:

It would be 'super cool' if we could use Mag Lev for most things in every day life.

Punbelievable!

I bought some magnets off the Internet last year that came with a health warning. Came together with so much force it would break your finger. Ended up smashing each other apart, and then the tiny shards sticking to the lining in my car.

Some seriously string stuff here:

http://e-magnetsuk.com/magnet_products/neodymium_m...