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MisterBig
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I place two permanent magnets on a desk so that their poles are orientated for attraction. I take my hands away and they move towards each other. Where does the energy come from? Are the magnets now slightly less magnetic?
Originally posted by sridhar_n
The energy comes from the potential energy stored in the field.
Uh, no it's not. When the two magnets are close, they are more massive. Thus, the react less strongly to the magnetic field, per Newton's second law. This seems to answer MisterBig's question.Originally posted by HallsofIvy
C'mon chroot. That true but irrelevant to the question!
being more massive does make the magnets accelerate more slowly, but it does not affect how magnetic they are, which is an intrinsic property of the metal. it doesn t change how strong the force they exert on each other it.Originally posted by chroot
Uh, no it's not. When the two magnets are close, they are more massive. Thus, the react less strongly to the magnetic field, per Newton's second law. This seems to answer MisterBig's question.
MisterBig was confused because he didn't understand where the potential energy went when he let go of the magnets and they snapped together. The answer is: mass.
- Warren
Hmm.. now I'm getting confused.Originally posted by lethe
for the mass of the system to change, energy must leave the system.
Originally posted by chroot
Since you're bringing them together slowly, there's no "bang" at the end when they touch, so there's neglibible energy lost to heat or sound. Am I correct that in the limit as the magnets are moved together at zero velocity, there is no energy lost?
normally, you have to provide new energy to separate the magnets again, since the energy released when they combine turned into thermal energy, which you cannot regain. however, if you set it up right, you can catch this energy (like if you put an ideal spring between the two magnets).Originally posted by MisterBig
Separating the magnets and letting them slam back together again makes sense to me. It’s when you allow the magnets to join and then separate them that bothers me. It seems a bit like cause preceding effect - the kinetic energy is released and then I provide the energy used in that release by separating the magnets.
the maximum of potential energy occurs when the separation is infinite.I think this is part of an ongoing problem i have with potential energy. At what distance is the potential energy between the 2 magnets at its maximum?
Originally posted by lethe
the maximum of potential energy occurs when the separation is infinite.
How do you bring them closer without expending some energy in another way? Friction? Springs? There's energy there.Originally posted by chroot
Since you're bringing them together slowly, there's no "bang" at the end when they touch, so there's neglibible energy lost to heat or sound. Am I correct that in the limit as the magnets are moved together at zero velocity, there is no energy lost?
- Warren
Originally posted by HallsofIvy
"near maximum mpe" doesn't make sense. Potential energy is always relative to some arbitrary reference.
so in a magnetic motor the magnetism will never be lost?sridhar_n said:No they are not less magnetic...The Total energy is always conserved.
Sridhar
The magnetism of attraction is a phenomenon in which objects with opposite magnetic poles are drawn towards each other. This occurs due to the force of magnetism, which is caused by the alignment of electrons within the material.
Magnetism of attraction works through the interaction of magnetic fields, which are created by the alignment of electrons in a material. When two objects with opposite magnetic poles come into proximity, the magnetic fields interact and cause the objects to be attracted to each other.
Magnetism of attraction has many practical applications, such as in electric motors, generators, and speakers. It is also used in magnetic levitation technology, which allows trains and other vehicles to float above magnetic tracks.
The strength of magnetism of attraction is affected by several factors, including the distance between the objects, the strength of the magnetic fields, and the type of material the objects are made of. In general, the closer the objects are and the stronger the magnetic fields, the stronger the attraction will be.
Yes, the magnetism of attraction can be explained by the laws of physics, specifically the laws of electromagnetism. These laws describe the relationship between electric and magnetic fields, and how they interact with each other to create the phenomenon of attraction.