perpetual motion

[James R]

"a contact force that fights the attraction"? Fighting sounds like hard "work"!

It only "fights" in the sense that it acts in the opposite direction. No work is involved.

In physics, "work" has a very specific and precisely-defined meaning. It is not used in the same loose way that your average punter uses the term.

Specifally, the work done by a constant force $$\vec{F}$$ on an object moving through displacement $$\vec{s}$$ is:

$$W = \vec{F}\cdot\vec{s}$$

In particular, if the object is not moving then s=0 and so is W.

 

[Physics confusion]

Hi again guys. i've just being reading through, and i am curious to know whether you think a "close to" perpetual motion device is possible.

 

[Read-Only]

Hi again guys. i've just being reading through, and i am curious to know whether you think a "close to" perpetual motion device is possible.

Nope, not even remotely. Besides the deeper complexities (like the second law of thermodynamics) that make it impossible, it's most obvious foe is plain old simple friction.

 

[prometheus]

To expand on this a bit, the maximum efficiency of a heat engine (an engine that has a "hot" reservoir and a "cold" reservoir) is given by Carnot's theorem. Other things that produce energy without exchanging heat like batteries are still bound by the first and second laws of thermodynamics.

 

[arfa brane]

In truth, it's just a very simple matter of energy being expended when motion is created in resistance to the fields you mentioned. And that energy is dissipated in the form of heat. Period.

The simple matter is that energy being "expended" or "dissipated" is the same as energy being exchanged. Energy doesn't disappear.
Where does heat "go" when it dissipates? Into the environment, right? So heat is exchanged with the environment, and the heat your muscles generate is an exchange of the energy you do, as work, when you pull magnets apart.

You probably haven't ever understood this, which is why your objection looks moronic. That education you think you got looks a bit half-arsed, I have to say.

My point was that you can't store energy and use it to generate more energy, because of, as I mentioned, the exchange of energy between systems, and the environment into which heat dissipates or is expended is a system.

Please stop pretending to be some kind of authority, because you aren't.

 

[Read-Only]

The simple matter is that energy being "expended" or "dissipated" is the same as energy being exchanged. Energy doesn't disappear.
Where does heat "go" when it dissipates? Into the environment, right? So heat is exchanged with the environment, and the heat your muscles generate is an exchange of the energy you do, as work, when you pull magnets apart.

You probably haven't ever understood this, which is why your objection looks moronic. That education you think you got looks a bit half-arsed, I have to say.

My point was that you can't store energy and use it to generate more energy, because of, as I mentioned, the exchange of energy between systems, and the environment into which heat dissipates or is expended is a system.

Please stop pretending to be some kind of authority, because you aren't.

Ha-ha! Take a look in the mirror, bub - you're the ONLY one that's pretending here!

Even though you've actually got a part of it right you are still doing little more than making yourself look undereducated and foolish.

Certainly any work done results in the release of heat and that heat is dissipated into the environment. BUT it's statements you made like "You exchange work for magnetic energy when you pull a fridge magnet away from the metal door" and this: "Likewise if you move in a gravitational field, you are doing work by exchanging energy with the field." Rubbish!

In both of those statements you are explicitly stating that a person is EXCHANGING - meaning sending some - energy into the field that is resisting you. And that's purely insane. If such a ridiculous thing happened, most of the human energy expended over the eons would have greatly increased the gravitational pull of the Earth since you have us all sending energy into it (by "exchanging energy with the field").

Perhaps English is not your native tongue and you actually meant to say "expended" energy as opposed to your "exchanged" - just as I suggested in my first reply to you. :shrug:

 

[James R]

It's important to realise that energy is not a substance. It's an accounting system.

Potential energy (e.g. in a gravitational field) is really configuration energy, which is just a way of summarising the separation between objects and quantifying how much useful work you can get out of that configuration.

 

[arfa brane]

In both of those statements you are explicitly stating that a person is EXCHANGING - meaning sending some - energy into the field that is resisting you. And that's purely insane. If such a ridiculous thing happened, most of the human energy expended over the eons would have greatly increased the gravitational pull of the Earth since you have us all sending energy into it (by "exchanging energy with the field").

When you exchange energy with gravity, you move around. Otherwise if the energy "went into the field" as you assume, you wouldn't move and the field's energy would increase.

This is not what happens when energy is exchanged, instead you gain kinetic energy (of motion). You would not be able to walk around otherwise, and you can't walk in empty space, right? You can't walk on the surface of a "non-gravitational" sphere either.

A fixed magnet has a constant magnetic field. It doesn't increase as you move a magnet close to a metal surface, because the motion is an exchange of energy with the field--you give the magnet (or the metal surface) kinetic energy, and the field potential changes, not the field itself. It changes because energy is exchanged "with" the field, which we observe as energy changing from one form to another "in" the field.

 

[Emil]

There are three kind of perpetual motion machine.
The first and second kind is imposible.
The third kind it is theoretically possible but practically impossible to achieve.(For example: an oscillating circuit in a superconductor.)

 

[Read-Only]

When you exchange energy with gravity, you move around. Otherwise if the energy "went into the field" as you assume, you wouldn't move and the field's energy would increase.

This is not what happens when energy is exchanged, instead you gain kinetic energy (of motion). You would not be able to walk around otherwise, and you can't walk in empty space, right? You can't walk on the surface of a "non-gravitational" sphere either.

A fixed magnet has a constant magnetic field. It doesn't increase as you move a magnet close to a metal surface, because the motion is an exchange of energy with the field--you give the magnet (or the metal surface) kinetic energy, and the field potential changes, not the field itself. It changes because energy is exchanged "with" the field, which we observe as energy changing from one form to another "in" the field.

Sure, I know all of that. But I still say your problem is that you don't know the difference between "exchange" and "expend."

Simply put, doing work requires an expenditure of energy - NOT an exchange with a field.

 

[Emil]

You really understand the law of conservation of energy?

The law of conservation of energy is a law of physics. It states that the total amount of energy in a system remains constant over time (is said to be conserved over time). A consequence of this law is that energy can neither be created nor be destroyed: it can only be transformed from one state to another. The only thing that can happen to energy in a system is that it can change form: for instance chemical energy can become kinetic energy.

 

[wellwisher]

One socially acceptable way to create perpetual motion is by making use of the concept of relative reference. For example, we will accelerate an automobile to 100km/sec. The passenger looks out and notices the person with the flag, standing at the starting line, appears to be moving at 100km/sec. This relative motion was inferred since the car rides smoothly, so they assume they are the stationary reference.

If we do an energy balance, we know, from direct observation, only the car received the needed energy for the acceleration. The person at the starting line did not receive any. The relative reference assumption violates the energy balance of each reference, since it takes way energy from one reference and creates it in another reference. This is the beauty of it, since this allows perpeual motion. If we assume reference was relative, we can turn the stationary person into a perpetual motion machine; Without any energy, the stationary reference will magically gain teleported energy so we can have a person moving at 100kmsec.

Using that perpetual motion energy, we can then do other extrapolations so we can get the energy back. For example, if this person needed to stop and go from 100kmsec to 0 km/sec, the braking energy could heat the brake pads to a certain temperature. We could also make use of hybrid technology to store the X amount of perpetual motion energy into a battery, etc. Or we can convert this to dark energy.

If we needed more energy, all we need to do is get the person in the car to open their eyes wider, beyond the person at the starting line. They need to also look at all the other race cars that are parked nearby. We can multiply the energy in the moving car (real energy balance) into the perpetual motion energy of dozens of moving cars. With this energy amplification we can solve the world's energy problems.

 

[Emil]

One socially acceptable way to create perpetual motion is ...

This is the beauty of it, since this allows perpeual motion.

Using that perpetual motion energy..

We could also make use of hybrid technology to store the X amount of perpetual motion energy into a battery, etc. Or we can convert this to dark energy.

We can multiply the energy in the moving car (real energy balance) into the perpetual motion energy of dozens of moving cars. With this energy amplification we can solve the world's energy problems.

LOL....:roflmao: You kidding, right?

 

[AlexG]

One socially acceptable way to create perpetual motion is by making use of the concept of relative reference

Socially acceptable?:shrug:

Do you really have any idea what you're saying?

 

[wlminex]

From Arfa Brane #25:

"Please stop pretending to be some kind of authority, because you aren't."

All forum participants (including myself!), wannabe "research scientists", real scientists, and other self-effacing "experts"- please imprint AB's suggestion in your neural matter!!

wlminex

 

[DRZion]

Don't mind if I do!

Hi again guys. i've just being reading through, and i am curious to know whether you think a "close to" perpetual motion device is possible.

I would say definitely yes. There is proof that the second law of thermodynamics can go in reverse. This is a certified, mathematically proven fact called stated as the fluctuation theorem. Also, nobel prize winners have themselves stated their dissatisfaction with the 2nd law, and a few have outright called it defunct and have in their work provided evidence to its contrariness.

There are three kind of perpetual motion machine.
The first and second kind is imposible.
The third kind it is theoretically possible but practically impossible to achieve.(For example: an oscillating circuit in a superconductor.)

That is correct, there are three kinds! But, while the last one is probably impossible I am certain the second is possible, and there is some reason to believe the first is possible too.

Nope, not even remotely. Besides the deeper complexities (like the second law of thermodynamics) that make it impossible, it's most obvious foe is plain old simple friction.

Ah, but friction is not a problem if a machine uses heat as fuel!

It can be demonstrated by a simple illustrative example of a ship burning at sea. The sailors have to put the fire out, and naturally they use sea water for this purpose. It doesn't matter if they spill some of the water from their buckets before reaching the fire - it will only flow back into the sea!
It is the same with heat and perpetual motion of the second kind - friction doesn't deplete the heat sink, it restores it. For this reason fuel efficiency is 100%.

 

[leopold]

Ah, but friction is not a problem if a machine uses heat as fuel!

ah but friction IS a problem, no matter WHAT the fuel is be it uranium or ice cubes.

 

[DRZion]

ah but friction IS a problem, no matter WHAT the fuel is be it uranium or ice cubes.

No. If highest entropy heat is the fuel source then friction is not a problem... at least in terms of fuel efficiency. Of course, friction is usually a problem which has to be reckoned with in any working machine.

 

[arfa brane]

But I still say your problem is that you don't know the difference between "exchange" and "expend."

No, that's your problem.
When a person or an engine "does work", the old-fashioned way of describing this is that you expend energy, since work = energy. But more precisely, work is an "output" of energy that "does" something useful.
An engine exchanges heat, with parts of itself and the environment. That last is true because an engine cannot be a closed system, you can't get anything "out" of a closed system. A heat engine exchanges energy with a matter field, whether the matter is the engine itself (i.e. the exchange "does work" internally), the exchange medium (a fluid usually), or the environment. All these are made of matter, and matter is a field, therefore a heat engine exchanges energy with a field.

An object in free fall above the surface of the earth reaches absolute velocity, because it's exchanging kinetic energy with the atmosphere--another matter field. It free falls in the first place (say from a fixed point of rest) because of gravitational energy that "exchanges" the object's potential energy for kinetic energy.

There are no solid objects, and no particles, there are only fields exchanging energy.
That's what E = mc[sup]2[/sup] actually means.

 

[Read-Only]

No, that's your problem.
When a person or an engine "does work", the old-fashioned way of describing this is that you expend energy, since work = energy. But more precisely, work is an "output" of energy that "does" something useful.
An engine exchanges heat, with parts of itself and the environment. That last is true because an engine cannot be a closed system, you can't get anything "out" of a closed system. A heat engine exchanges energy with a matter field, whether the matter is the engine itself (i.e. the exchange "does work" internally), the exchange medium (a fluid usually), or the environment. All these are made of matter, and matter is a field, therefore a heat engine exchanges energy with a field.

An object in free fall above the surface of the earth reaches absolute velocity, because it's exchanging kinetic energy with the atmosphere--another matter field. It free falls in the first place (say from a fixed point of rest) because of gravitational energy that "exchanges" the object's potential energy for kinetic energy.

There are no solid objects, and no particles, there are only fields exchanging energy.
That's what E = mc[sup]2[/sup] actually means.

I suppose I will have to be blunt. Again, some of what you say is correct. But the rest is nonsense because you use very specific terms COMPLETELY in a wrong fashion: just like you do with "exchange" and "expend." :bugeye:

In this round you use the term "absolute velocity" - which is stupid because there is no such thing - where intelligent and educated people would rightly say "terminal velocity." Those two terms have no relationship.

And then you smugly attempt to claim that "There are no solid objects, and no particles..." because you do NOT even understand the meaning of the formula you base your misdirected belief on. What that formula is REALLY saying is that solid objects and particles (better said as "mass") and energy are interchangeable! Only a truly under-educated person would make such an idiotic mistake in this day and age!!!