Perpetual Energy

[johnfp]

My discussion on "The Final Theory" (which, please to not discuss here), brings me to an idea that Newtonial physics states is totally possible.

 

Find a meteor or a large body of mass in our solar system which has enough mass to have ample gravity and in which it would be possible to drill all the way through. Let's say the diameter of the hole is about 1 foot. Now slide a tube consisting of a coiled wire from end to end alternating with supermagnets. Then take another supermagnet and drop it into the hole. This large body is in space so their is no air friction. The magnet should drop, slow and center and stop before coming out the other side. Then repeat. The magnets in the tube keep the droping magnet from touching the sides of the tube. At the same time, the magnet falling back and forth is creating an electrical current in the coiled wire.

 

Free, everlasting energy.

 

Where are my flaws?

[CraigD]

Where are my flaws?

The flaw is a simple mechanical one.

 

The described machine is essentially a pendulum. The energy of the moving mass relative to the large body consisting of a potential and a kinetic energy part, with the total energy remaining constant. When the mass is stationary at the top of each “swing”, all of the energy is in potential form. When it passes through the center of the tube-drilled large mass, all of the energy is in kinetic form.

 

If no force other than gravity acted on the moving mass, it would bob from surface to opposite surface forever. However, since we want to get power from it, a force must act on it – in John’s example, the magnetic force of the moving magnet on the fixed coils that induces a usable electric current in them. The total energy of the moving magnet would be reduced by the extracted electric energy, causing it to bob lower and lower, finally coming to rest at the center of the tube.

 

Specifically, assuming a uniform density of a spherical large mass, the potential energy of the small mass at its surface is

 

[math]E_P = \frac{3GMm}{2r}[/math]

where [math]G[/math] is the gravitational constant,

[math]M[/math] is the mass of the large body,

[math]G[/math] is the mass of the moving body,

and [math]r[/math] is the radius of the large body.

(see Gravitational potential due to rigid body for a derivation of this)

 

So, taking a large asteroid such as 4 Vesta and a roughly car/large artillery shell-sized 1000 kg moving mass as an example, the starting potential energy of the system would be about

 

[math]\frac{3 \cdot 6.7 \times 10^{-11} \cdot 2.7 \times 10^{20}}{2 \cdot 500000} \dot= 5.4 \times 10^{7}[/math] J.

 

This is enough energy to light a 100 W light bulb for about 540000 seconds, or 6.25 days.

 

Devices similar to the one John describes are actually fairly common on newer amusement park rides, where they are used as a magnetic brakes. In this application, the extracted electric energy is wasted as heat in a conductive metal plate that acts like the coil in John’s description. Because these brakes have no moving parts and apply a force proportional to the speed of the vehicle being braked, they are favored due to their high reliability and inherent safety.

[Little Bang]

Excellent answer Craig.

[Janus]

Just to add to what CraigD has already stated.

 

As The magnet drops through the hole, it will induce a current in the coil. But this current, in turn, turns the coil into an electromagnet itself, one with a polarity that will oppose the movement of the magnet. This will retard the fall of the magnet and its subsequent climb back out ont he other side. The upshot being that the magnet will not reach the same height at the top of its path on the other end. On the return trip the same thing happens and the magent comes up even further short. It continues to lose height on each trip unitl it rests in the center. How many trips it will take will depend on how well the magnet can induce current in the coil.

 

The amount of total energy that could be extracted is as has already been pointed out.

 

So, sorry, no perpetual energy source.

[johnfp]

Thank you Craig!

 

So essentially mechanically the act of the magnet on the coil actually causes a drag on the magnet because some of the kinetic energy is being used to push the electrons foward in the coil.

 

In other words, if the tube were in space, no gravity, and I was pushing the magnet manually down the tube I would feel resistance from the fact of the magnet pushing the electrons in the coil alone?

 

Does that make sense?

[johnfp]

Just to add to what CraigD has already stated.

 

As The magnet drops through the hole, it will induce a current in the coil. But this current, in turn, turns the coil into an electromagnet itself, one with a polarity that will oppose the movement of the magnet. This will retard the fall of the magnet and its subsequent climb back out ont he other side. The upshot being that the magnet will not reach the same height at the top of its path on the other end. On the return trip the same thing happens and the magent comes up even further short. It continues to lose height on each trip unitl it rests in the center. How many trips it will take will depend on how well the magnet can induce current in the coil.

 

The amount of total energy that could be extracted is as has already been pointed out.

 

So, sorry, no perpetual energy source.

 

Got it, thanks!

[arkain101]

Yep I think the answers here explain it really well and correct.

 

I will just add a basic law in mechanical related physics.

 

For every action, There is an equal and opposite reaction.

 

Or in other words.. As in your example Transforming motion into electricity: To acquire or gain electricity an equally perportional amount of motion must be lost. In this case it can be shown as

-Motion = +Electricity

+Motion = -Electricity

 

And to add a bit of a philisophical aspect to this topic:

 

There are systems that work almost endlessly like the solar system for example . It can be considered as great machine or system of moving planets around a sun. It is infact a system in motion. A relatively perpetual system. However it is not a system designed to have energy extracted from its operation as a whole. Rather it is the system itself that operates outside of a realm of opportunity, and also acts as the provider of this opportunity. The opportunity to develope systems that can be used to extract energy from. This is just as the universe is the perptual existence -that we can now contemplate- is required for a give and take (equal - opposite ) relationship to exist within this greater lasting system.

 

To summerize, A perpetual motion machine can be built, and they exist all around us. However, their purpose is to be experienced and provide opportunity for experience. The moment you attempt to extract energy from them, is the moment the perpetual system meets its doom.

[arkain101]

However do not this fool you in the concept of developing efficient devices or systems, which push towards operating on free energy 100% of the time.

 

A car for example can be engineered in such a way as to run on Heat, Wind, Solar, and Kenetic energy, all of which do not reduce the efficiency of the vehicles purpose. That is, motion.

 

A vehicles job is not equivelent to a physics equation. A vehicle must be capable to speed up and slow down in order to reach a destination. Therefore it is possible to acquire energy for free without affecting the way we drive cars.

 

So do not get discouraged by some statements proclaiming the impossibility and pointlessness of attempting to construct a system which operates for free relative to a human lifetime.

 

Which is of course the very purpose to engineering. Have it work efficiently and effectively throughout your life.

[Qfwfq]

In other words, if the tube were in space, no gravity, and I was pushing the magnet manually down the tube I would feel resistance from the fact of the magnet pushing the electrons in the coil alone?

Try spinning an alternator, first with its terminals disconnected and then shorted. Why does a car use more fuel (or get sluggish) with air conditioning switched on?

[UncleAl]

1) Time is homogeneous.

2) Noether's theorem.

3) Mass-energy is locally conserved

4) End of discussion.

 

STURGEON WAS AN OPTIMIST