Free energy

[ironizer]

when you have a magnet, say 5 inches off the ground, and the magnet weighs 5N. The amount of energy it took to lift lets say is X. Then you slide a nail under it, and gets pulled up. Now, the magnet and nail all togheder have, say 8Newtons, and so it has more potential energy. So when you release them, it drops and more kinetic energy is released than the energy you used to lift the magnet up. Where's the flaw on this? Seems good to me!

[mmalluck]

It's all "goo" especially when you realize Netwon's third law of motion.

 

For every action there is an equal and opposite reaction.

 

In this case the magnet is pulled down with the same force as the nail is pulled up. You have to apply a force to the magnet to keep it in place otherwise, it would be drawn towards the nail with the equal, but opposite force.

 

In addition, if we add the vector with which the nail moves to the vector the magnet moves, the sum of the forces equals zero. No energy was created.

[ironizer]

yeah but if the manget is resting on some object, the object doensn't need energy to hold the magnet up, Just like you don't have to plug in your chair before you sit on it in order to hold you up!

[mmalluck]

A force is still applied to the surface regardless if the magnet moves or not. No work is done, but the force is still applied.

 

If you look at the system as a whole, the net energy still remains at zero. The magnet and surface it's resting (the earth) will move with a resultant momentum equal to that of the nail in the opposite direction.

 

If I jump up off the earth, am I moving away from the earth, or is the earth moving away from me? Both are true. Both I and the earth move away from some initial frame of reference. The earth moves an incredably small amount because it's mass is so much greater and I move considerable more because i weigh less, but it still happens.

[mmalluck]

Blimey! I though of a better way of looking at this problem while I was in the bathroom (where all great thinking is done). You really have two types of potential energy here: gravitational potential and magnetic potential, you are merely trading one for the other.

 

Gravitiational potential energy has to do with the force an object will experiance (Fg) do to gravity, the mass of the object (m), and it's distance from some zero potnetial point (Hg).

 

Potental G = m*Fg*Hg

 

Magnetic potential, likewise, has to do with the mass of the object(m), the force it will experiance due to the magnetic field(Fmag) and it's distance from some zero potential point (Hmag). (I realize this is simplifying things a great deal but for the sake of this argument it should work)

 

Potential mag = m*Fmag*Hmag

 

In your system gravity and the magnetic force oppose eachother so...

 

total potential energy = Potental G - Potential mag

 

But get this, as you loose gravititational potential, you gain an equal amount of magnetic potential (you move the nail closer to the ground, so it looses gravitational potential, but the farther away from the magnet you move it, the more energy it will have as it comes crashing back to the magnet) and vise versa.

 

The total amount of potential energy is conserved in this system.

[YT2095]

what do you use to release the nails from the magnet?

 

^^^ there`s a Clue in there ^^^

[bascule]

what do you use to release the nails from the magnet?

 

A degausser. That doesn't use any energy, right?</sarcasm>

[swansont]

what do you use to release the nails from the magnet?

 

^^^ there`s a Clue in there ^^^

 

 

Understatement of the day, here.

 

It's a single-use device. You have energy stored in the field, and you're tapping into that. But you can do it only once.

[YT2095]

We have a Winner!

[ironizer]

Understatement of the day' date=' here.

 

It's a single-use device. You have energy stored in the field, and you're tapping into that. But you can do it only once.[/quote']

 

so what, it's still proving magnets have energy; i'm not suggesting that any work can be done with this stuff, it's very inefficient

[bascule]

so what, it's still proving magnets have energy; i'm not suggesting that any work can be done with this stuff, it's very inefficient

 

So what? We already use magnets to make electricity. It's not free energy; you still need to put more energy into turning a dynamo than you'll get out of it as usable electricity.

[swansont]

so what, it's still proving magnets have energy; i'm not suggesting that any work can be done with this stuff, it's very inefficient

 

That magnets have energy should surprise nobody at all.