A magnet that won't stop spinning?

In summary, the conversation discusses the possibility of a magnet-coil apparatus that could spin continuously. It is determined that this is not possible due to the laws of conservation of energy and internal forces cancelling out any external force.
  • #1
ARAVIND113122
54
0
A magnet that won't stop spinning??

what happens if a horseshoe magnet is fixed to a a coil such that there is a constant field through the coil?? The initial torque due to the field will spin the coil,but since the magnet is connected to the coil,it will keep sending a field through the coil at the same angle,further spinning the coil and then the process continues...the coil-magnet apparatus will keep on spinning. Isn't this possible??
 
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  • #2


...
 
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  • #3


By Jove! I think you've got something! Now, run with it!
 
  • #4


No, clearly this violates conservation of energy, so it won't work.
 
  • #5


Why would it violate the law of conservation of energy?The magnet is the source of energy.We are simply using the energy provided by the magnet.No energy is being "magically produced".
 
  • #6


No, nagnets do not expend energy by exerting a static force. A magnet is no more a source of continuous power than a spring.

Perhaps if you drew yourself a picture you'd see that what you are suggesting is like lifting yourself off the ground by pulling on your own shoelaces.
 
  • #7


But where does the magnet-coil model fail?What would actually happen if the set up is made and placed in a zero gravity environment.As long as the the magnet exerts force,the coil would spin.
 
  • #8


Nothing will happen. It will not spin because there is no external force to spin it.
 
  • #9


Hmm..but if the magnet were to be detached for a split second,it would spin.That brings me to a more fundamental question-why is there such a big difference between internal and external forces in this case?Why doesn't the internal force in the attached apparatus do anything?After all,it is a field through a magnet[is it because the coil applies an equal and opposite force?]
 
  • #10


ARAVIND113122 said:
Hmm..but if the magnet were to be detached for a split second,it would spin.That brings me to a more fundamental question-why is there such a big difference between internal and external forces in this case?Why doesn't the internal force in the attached apparatus do anything?After all,it is a field through a magnet[is it because the coil applies an equal and opposite force?]

What do you mean "spin"? What you are trying to describe just won't work. You are trying to create perpetual motion.
 
  • #11


By spin ,i mean that the coil will rotate so as to minimize magnetic flux through it.
Then again,why wouldn't the magnet-coil apparatus spin-is it because an equal force would be exerted by the coil,thus cancelling out torque due to the magnet?
 
  • #12


ARAVIND113122 said:
By spin ,i mean that the coil will rotate so as to minimize magnetic flux through it.
Then again,why wouldn't the magnet-coil apparatus spin-is it because an equal force would be exerted by the coil,thus cancelling out torque due to the magnet?

Yes. If the coil is correctly orientated within the magnet then there is certainly a torque ,due to the current, acting on the coil. For this same orientation and current direction however, the coil itself will induce it's own magnetic poles, which are perpendicular to the main magnet poles and with a N-S polarity directed so as to produce a counter torque on the main magnet.
 
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  • #13
ARAVIND113122 said:
That brings me to a more fundamental question-why is there such a big difference between internal and external forces in this case?Why doesn't the internal force in the attached apparatus do anything?
Internal forces always sum to zero. Try this:

Sit on a swivel chair.
Grab your left shoulder with your right hand.
Pull.

Do you start to spin?
 
  • #14


oh yes! i have realized my mistake! i had not thought about the opposite magnetic field.thank you very much
 
  • #15


russ_watters said:
Internal forces always sum to zero. Try this:

Sit on a swivel chair.
Grab your left shoulder with your right hand.
Pull.

Do you start to spin?

I've been sitting in my office chair trying this for a while now and can't seem to do it.

Am I doing it wrong? Do I pull or push my shoulder?
 
  • #16


nitsuj said:
I've been sitting in my office chair trying this for a while now and can't seem to do it.

Am I doing it wrong? Do I pull or push my shoulder?

Is this sarcasm? If so haha, if not it won't work anymore than reaching down and pulling your legs up will make you rise.
 

FAQ: A magnet that won't stop spinning?

How does a magnet keep spinning indefinitely?

A magnet that won't stop spinning is a result of its inherent magnetic properties. Magnets have two poles - a north pole and a south pole - and these poles are constantly attracting and repelling each other. When a magnet is in motion, the north and south poles are constantly changing positions, which creates a continuous spinning motion.

Can a magnet eventually stop spinning?

Yes, a magnet that seems to be spinning indefinitely will eventually slow down and stop due to friction and other external forces. The rate at which it slows down will depend on the strength of the magnet and the surface it is spinning on.

What factors affect the spinning speed of a magnet?

The spinning speed of a magnet can be affected by various factors such as the strength of the magnet, the surface it is spinning on, the presence of other magnetic fields, and the force of gravity. Additionally, any external forces such as air resistance or friction can also impact the speed of the spinning magnet.

How can a magnet spin without any apparent external energy source?

A magnet that won't stop spinning may seem to be a perpetual motion machine, but in reality, it is not. The spinning motion is a result of the magnetic forces between the poles of the magnet, which are constantly in motion due to their inherent properties. The energy that keeps the magnet spinning comes from its magnetic field, not from an external source.

Is a magnet that won't stop spinning useful for anything?

While a magnet that keeps spinning may seem like a novelty, it has practical applications in various devices such as generators, motors, and compasses. These devices use the spinning motion of a magnet to generate electricity or to indicate direction. In addition, studying the spinning behavior of magnets can also help scientists understand more about magnetism and its properties.

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