Spinning Magnets in Space: Physics & Hydro Generator

[grimofdoom]

I havnt taken physics in a while and cannot remember much. But i came here to see if an idea i had was possible. The idea is that if you were to spin a magnet in space(becasue from what i remember if you spin an object in space it continues non-stop(i have bad memory though)) you can use the spinning magnet like a hydro generator, to create limitless electrical energy. But first i want to know if you were to spin a magnet in space if(pt1) it will continue to spin non-stop and (pt2) it could be used like a hydro generator were it has coils around it to create electricity. Please answer this if possible.

 

[Whovian]

Whenever one extracts energy from a system, the energy must (Correction: come from somewhere). In this case, the magnet's spinning will slow down.

 

[grimofdoom]

Im a little slow,can you explain it a little more?

 

[Whovian]

So, basically, Conservation of Energy implies this energy must come from somewhere. The only place it could come from in this situation is the rotational kinetic energy of the magnet.

 

[grimofdoom]

Ok,i see now. Thank you.

 

[grimofdoom]

But if you take part of the gatherd energy to start it up again, it would only create the same amount of electricity used to respin it again?

 

[Whovian]

But if you take part of the gatherd energy to start it up again, it would only create the same amount of electricity used to respin it again?

Actually, due to friction, you'd get less energy back.

 

[grimofdoom]

But were would the energy from friction go? I know space is cold so the energy from friction would create heat but be gone from the cold of space.

 

[russ_watters]

Both motors and generators are basically the same device: rotating electromagnets that convert energy between electrical and mechanical. When you apply electricity to a motor, it rotates. If you want it to produce more torque, it will need more electricity. Generators work the same way: if you want to extract more electrical energy, they will produce a stronger magnetic field, which will require more input torque to counteract.

It surprises me that while most people are aware of how motors work (and don't expect a violation of conservation of energy), this question is very common when it comes to generators.

 

[Chronos]

It would be like using an electric motor to power an electric generator to power the electric motor. It doesn't work. Extracting energy from a motor creates a braking torque on the motor. Drawing energy from a generator also creates a breaking torque on the generator [its just a reverse wired electric motor].

 

[Whovian]

But were would the energy from friction go? I know space is cold so the energy from friction would create heat but be gone from the cold of space.

It would just get dissipated, and while the heat wouldn't have much of an effect on the surroundings, this doesn't affect how much heat energy was released.

 

[russ_watters]

The energy is not being dissipated as heat, it is being converted from mechanical (kinetic) to electrical.

 

[Whovian]

The energy is not being dissipated as heat, it is being converted from mechanical (kinetic) to electrical.

And the quote I was replying to was asking where the energy from the friction would go.