- #1
entropy1
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If a static magnet attracts an object A, where does the kinetic energy that A acquires come from?
In summary, the kinetic energy acquired by an object A when it is attracted by a static magnet comes from the potential energy that was previously there. This potential energy is brought with the magnet, and if A was already stuck to the magnet, retracting it would increase the potential energy. In the case of using a ferromagnetic material to produce an austenitic steel, the potential energy undergoes a phase transition and there is energy accompanying this transition. The potential energy also depends on the strength of the magnetic field and crafting a magnet does not necessarily require enough energy to account for the acquired potential. Additionally, potential energy is not the same as potential and potential energy is not a conserved quantity, while total energy is.
- #2
DrClaude
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It comes from the potential energy that was previously there. The original state, before the object started moving, had a higher potential energy, so you can try to trace where that energy came from.
- #3
stockzahn
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DrClaude said:
Due to this thread I actually had a thought that never came up: If you have a ferromagnetic material like iron in a magnetic field and you treat it and add certain components to produce an austhenitic steel (which is not ferromagnetic). What happens to the potential energy then? Especially due to the fact that magnetic fields have an infinite range ... It seems to be analogeous to switching of the mass of the body in a gravitational field - what's my mistake?
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- #4
entropy1
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I don't understand, so let me ask a second question: the potential is brought with the magnet, right? Without magnet de potential energy wouldn't be there. So where does the magnet get its potential to produce potential energy in A from?DrClaude said:
I can image that, if A was stuck to the magnet in the first place, the potential energy would increase by retracting it from the magnet. So then is the sticking to the magnet somehow the natural state of A?
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stockzahn
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entropy1 said:
That seems to be similar with gravitation and the electric field. If you have two masses or two charges respectively, there is a potential between them - if one "vanishes" also the potential energy is gone. If they stick very close together, the potential energy is zero, if they are retracted from each other you have to spend work.
- #6
A.T.
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It's the minimal energy state.entropy1 said:
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Vanadium 50
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stockzahn said:
You are describing a phase transition, just like melting ice or boiling water. There's energy accompanying a phase transition.
- #8
Vanadium 50
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entropy1 said:
Same place a spring does.
- #9
stockzahn
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Vanadium 50 said:
Wouldn't that mean that depending on the strength of the magnetic field the ferromagnetic body is influenced by, the phase transition needs more or less energy?
- #10
entropy1
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Is it correct to say that objects that are attracted by a magnet already have this potential? For instance: if we craft a magnet, from then on it gives all metal in the universe some more potential. If that is so, wouldn't crafting the magnet require enough energy to account for that acquired potential?Vanadium 50 said:
Does spacetime structure have to do with this also?
- #11
russ_watters
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Yes.entropy1 said:
entropy1 said:
No, the magnet does not have potential energy, the system does (magnet + whatever it is attracted to). Also, "potential" is not "potential energy". So having "potential" does not require generation of "energy".
- #12
entropy1
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So potential energy is not a conserved quantity? (After all, you can always dig that hole deeper 
)
)- #13
Vanadium 50
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Total energy is conserved. How you divvy it up is not.
FAQ: Where does the energy come from? (magnet)
1. Where does the energy come from in a magnet?
The energy in a magnet comes from the alignment of its microscopic magnetic domains. These domains contain electrons with a specific spin, which creates a magnetic field. When these domains are aligned, they create a stronger magnetic field and therefore more energy.
2. How is energy produced in a magnet?
Energy is produced in a magnet through the movement of electrons. When a magnet is placed near a conductive material, such as a wire, the magnetic field will cause the electrons in the wire to move, creating an electrical current. This movement of electrons is what produces energy.
3. Can a magnet run out of energy?
No, a magnet cannot run out of energy. The energy in a magnet is a result of the alignment of its microscopic magnetic domains, which are a fundamental property of the material. As long as the material remains intact, the magnet will retain its energy.
4. What is the source of energy in a permanent magnet?
The source of energy in a permanent magnet is the alignment of its magnetic domains, which is a result of the material's atomic structure. This alignment creates a magnetic field, which is the source of the magnet's energy.
5. How does a magnet create energy?
A magnet creates energy through the movement of electrons. When a magnet is moved near a conductor, such as a wire, the magnetic field will cause the electrons in the wire to move, creating an electrical current. This current can then be used to power devices or perform work.