# Conservation of Energy and Gravitation

## Recommended Posts

The Energy Conservation Law states that energy cannot be created or destroyed, but may be transformed. A hydroelectric plant generates electrical energy, where does it come from?

The weight of water (due to gravity) turns the turbines that turn the generators, so it seems the "force" of gravity is the driving force that produces the electrical energy.

But, then from where does this force come? Can a force that does mechanical work come endlessly out of nowhere? Is the apparently endless energy created out of nowhere, in violation of the Energy Conservation Law, or is the electrical energy actually being transformed out of something else, and if so what?

What is going on here?

Hint: This question reduces to "where does (the force of) gravity and gravity itself come from?"

Sir Isaac Newton in his famous "Letters To Bentley" clearly rejected the concept of "action at a distance" for gravity.

Any and all answers based on science are welcome.

Phillip Duke Ph.D.

Edited by phildukephd

##### Share on other sites

Where does gravity come from is not a science question. It is one of metaphysics. Science observes that mass causes gravity (Newtonian). It's not in the business of explaining why.

##### Share on other sites

The point where energy is put into the system is when water is moved from the ocean and moved up on the mountain. As far as I know the energy for that ultimately comes from the sun's solar irradiation.

##### Share on other sites

It's not endless energy. The energy stops when the water runs out, and to get more you need to bring more water up the hill, i.e. expend mechanical energy to increase the water's potential. Or you can evaporate the water by supplying heat energy, and have it condense and precipitate at the top of the hill. (The sun can do this for you.) Either way you need to expend energy to get water to the top of the hill for the generator to be of any use.

##### Share on other sites

This is a classical physics forum and for fun and interest I asked a question that Einstein answered.

The question I asked is quite valid- the Sun's energy only works against gravity to make rain and snow that fall to earth and sit there or run downhill, the hydroelectric generator's energy comes from the force of gravity, it is the force that turns the generators, keeps us in orbit and on the Earth's surfavce, keeps the Sun from exploding, etc. So gravity is very important, and if you want to know where it comes from read the work of that very great scientific genius Albert Einstein.

Hint: The Energy Conservation Law remains valid, otherwise it would no longer be taught, gravitic energy comes from something else. Just as matter can be converted to energy, something else is converted to gravity. The question is, what?

The question of why is harder to answer than how, but it is important and science tries its best to answer both. How gravity works was established by Newton, Einstein wanted to know and found out why.

At the first derogatory reply Post I will not Post here again- in my Forum experience that will come next in the replies to this Post. If you want to know how the universe works in terms of physics, read about Relativity. It is very well worth your time.

Good luck.

Phillip Duke Ph.D.

##### Share on other sites

Hint: The Energy Conservation Law remains valid, otherwise it would no longer be taught, gravitic energy comes from something else. Just as matter can be converted to energy, something else is converted to gravity. The question is, what?

Are you asking a genuine question or are you trying to pose riddles that you have suggestions as to what the answers are?

If it is the latter, then maybe you should post about that so that we can discuss these ideas. It sounds like you are hinting at something we should discuss.

##### Share on other sites

There's a common misconception between force and work/energy. Energy is a conserved quantity, but force is not. There is no issue with there being a continuous force exerted between objects; if there is no work being done, then there's no energy being dissipated. Nothing "runs out". An object can sit on a surface, feeling the force of gravity, for an indefinite amount of time, much like a magnet can remain stuck to a refrigerator. It's not "using anything up" by doing so.

An object doing work while falling must have had work done on it to get it into its original position. It's not endless.

##### Share on other sites

The Energy Conservation Law states that energy cannot be created....

It was created once though, no?

##### Share on other sites

gravitic energy comes from something else.

Unless you mean potential energy, I think you had best 1) define what 'gravitic' energy is and 2) ask the mods to move this thread to speculations because unless the first clause of this sentence is true, then you are talking about something very much not mainstream and therefore should be categorized as a speculation.

Edited by Bignose

##### Share on other sites

In reply to the posts, I am pleased that no one has personally attacked me, and the replies show thought as well as a certain misunderstanding regarding science. Science's function is to increase knowledge because lknowledge is power and science's purpose is to bemefit humanity by giving it power. The question why can be very important in addition to the question how, and both are subject to scientific investigation.

The basis of the question I posed, where is the electrical energy coming from in relation to gravity, is obvious in the case of a hydroelectric plant operated by tidal flow. Open the gates and let seawater in until peak high tide, then close the gates, and ar low tide allow the water to leave after turning a turbine.generator. This is a clear example of gravity producing electrical energy. The Sun's energy is not involved. Tides are caused by the Moon's gravity, with a small contributuion from the Sun's gravity. Again, where does the energy come from? More directly, where does the force of gravity come from?

It is "the force of gravity" that turns the sea water driven turbines that generate electricity, where does this force which is converted to electrical energy come from? Hint: The Conservation Law is not violated, something else is converted to gravity, the question is what? What else is there?

This question was posted here to stimulate thought, but it actually belongs under Relativity. Doctor Albert Einstein's Relativity Theories answered this question and more. When the reply nposting is over I will briefly post his explanation, which is accepted and believed to be true. Einstein was a genius and his concepts are very hard to grasp, but well worth the trouble. You will be amazed!

<paragraph advertising website removed - please recheck rules especially Posting - Rule 7.>

Best regards,

Phil Duke PhD

Edited by imatfaal

##### Share on other sites

Are you referring to Einstein's pseudotensor?

##### Share on other sites

Post#1

The Energy Conservation Law states that energy cannot be created or destroyed, but may be transformed. A hydroelectric plant generates electrical energy, where does it come from?

The weight of water (due to gravity) turns the turbines that turn the generators, so it seems the "force" of gravity is the driving force that produces the electrical energy.

Post#5

This is a classical physics forum and for fun and interest I asked a question that Einstein answered.

Post#10

The basis of the question I posed, where is the electrical energy coming from in relation to gravity, is obvious in the case of a hydroelectric plant operated by tidal flow. Open the gates and let seawater in until peak high tide, then close the gates, and ar low tide allow the water to leave after turning a turbine.generator. This is a clear example of gravity producing electrical energy. The Sun's energy is not involved. Tides are caused by the Moon's gravity, with a small contributuion from the Sun's gravity. Again, where does the energy come from? More directly, where does the force of gravity come from?

This is a disappointing question since you have not properly stated the conditions at the outset.

In particular you did not specify a tidal hydrogenerator in post#1, but delayed introducing this new fact in post#10

Now I am trying to reassure a young student in another thread here that he or she has every right to expect academic questions to contain sufficient information to uniquely determine the answer.

How does this play with that?

I hold that I could build a hydro electric generator that does not depend upon gravity for its function and that weight play no part in the machine.

So my hydroelectric generator could operate either in the presence or absence of gravity.

So where would I get the energy?

Edited by studiot

##### Share on other sites

This is a disappointing question since you have not properly stated the conditions at the outset.

In particular you did not specify a tidal hydrogenerator in post#1, but delayed introducing this new fact in post#10

Now I am trying to reassure a young student in another thread here that he or she has every right to expect academic questions to contain sufficient information to uniquely determine the answer.

How does this play with that?

I hold that I could build a hydro electric generator that does not depend upon gravity for its function and that weight play no part in the machine.

So my hydroelectric generator could operate either in the presence or absence of gravity.

So where would I get the energy?

I was initially thinking undershot waterwheel - but I cannot think of a realistic way for the watercourse to be driven except by gravity.

Those wave power generators - worm like things that flex and the flexion drives dynamos? But the waves rely on climate systems which rely on gravity (hot air rises etc)

Unless you are thinking hydroelectric includes the use of expanding fluids as per a turbine?

Nope - I am stumped

##### Share on other sites

Unless you are thinking hydroelectric includes the use of expanding fluids as per a turbine?

Nope - I am stumped

Turbines operate on momentum, not weight.

All you need is a stored energy source you can take into space with you (plus the water of course), to make it operate in space.

##### Share on other sites

Turbines operate on momentum, not weight.

All you need is a stored energy source you can take into space with you (plus the water of course), to make it operate in space.

Sorry confused - are you saying turbines were what you had in mind?

As an aside; some might quibble whether your question is actually answerable - this is the definition given in wikipedia

Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water.

But I think that is a needlessly narrow definition. My Collins dictionary on my desk has that as the 1st definition but the 2nd is wider and would include turbines

##### Share on other sites

What a nonsensical definition.

Hydroelectricity is the generation of electricity by the movement of water.

If I pumped water uphill, through a turbine, would that not be hydroelectricity?

But nothing requires the movment of water to be gravitationally induced.

I was actually thinking of compressed air (like any good diver would).

Of course using the compressed air to move the water through the turbine is less efficient than using the air directly, but the question required the water.

It did not require gravity.

Edited by studiot

##### Share on other sites

Tides are caused by the Moon's gravity, with a small contributuion from the Sun's gravity. Again, where does the energy come from?

The tidal interaction with the moon is slowing the earth's rotation. That's ultimately the source of the energy. (it's also making the moon recede; angular momentum must be conserved)

More directly, where does the force of gravity come from?

Perhaps you could participate in the discussion that's already taken place in addressing this, rather than simply re-asking it.

##### Share on other sites

The tidal interaction with the moon is slowing the earth's rotation. That's ultimately the source of the energy. (it's also making the moon recede; angular momentum must be conserved)

If that's truly the only source, then when Earth will be spinning at the same rate as Moon orbit around Earth (so they're facing always the same side), tidal should vanish.

But I don't think so- we can easily imagine situation when both objects are facing always the same side to each other, but once they're closer, other time they're further from each other. And in such case also there should be tidal.

Edited by Sensei

##### Share on other sites

If that's truly the only source, then when Earth will be spinning at the same rate as Moon orbit around Earth (so they're facing always the same side), tidal should vanish.

But I don't think so- we can easily imagine situation when both objects are facing always the same side to each other, but once they're closer, other time they're further from each other. And in such case also there should be tidal.

How are they closer or further? And how big of an effect will that be?

##### Share on other sites

If that's truly the only source, then when Earth will be spinning at the same rate as Moon orbit around Earth (so they're facing always the same side), tidal should vanish.

Yeah. Only problem is it is happening so slowly that the Sun will have expanded prior to the process reaching completion.

I can't help but wonder what it would have looked like from the ground. Imagine people taking vacations to "moonside" Earth to see it hanging in the sky.

Edited by Endy0816

##### Share on other sites

How are they closer or further?

You know - apogee, and perigee..

Similar like between Earth and Sun, we have perihelion, and aphelion.

According to this website:

Max perigee is 356921 km

and

max apogee is 406568 km

406568/356921 = ~ 14% (~ -7... +7% from average)

And how big of an effect will that be?

Interesting question.

If tidal forces are caused by only distance between our two (or more) massive objects, the strongest tidal should be at perigee or in perihelion.

Yeah. Only problem is it is happening so slowly that the Sun will have expanded prior to the process reaching completion.

Tidal is not Earth-Moon phenomena.

Between Jupiter and Io it also happens.

http://en.wikipedia.org/wiki/Io_(moon) (second paragraph).

We can easily imagine 2 planets system in outer space, var away from any living stars, orbiting around elliptical orbits.

Edited by Sensei

##### Share on other sites

Well, yes...

I was talking about what would have been the eventual mutual tidal lock between the Earth and Moon.

Locking of the larger body

The tidal locking effect is also experienced by the larger body A, but at a slower rate because B's gravitational effect is weaker due to B's smaller size. For example, Earth's rotation is gradually slowing down because of the Moon, by an amount that becomes noticeable over geological time in some fossils. [1] The process is still happening and has significantly slowed down the rotation of Earth since the beginning of its existence. Current estimations are that this has helped lengthen the Earth day (together with the tidal influence of the Sun) from about 6 hours to the current 24 hours. And at this moment, atomic clocks show that Earth's day lengthens by about 15 microseconds every year. [2] Given enough time, this would create a mutual tidal locking between Earth and the Moon, where the length of a day has lengthened and the length of a lunar month would have shortened to a point where they are the same length. But it is happening so slowly that Earth is not expected to become tidally locked to the Moon before the Sun becomes a Red giant and engulfs Earth and the Moon.[3][4]

http://en.wikipedia.org/wiki/Tidal_locking

##### Share on other sites

Introducing tidal energy generation has somewhat side tracked the question, which is still this: Since the "force of gravity" can be employed to do work and generate electrical energy, and assuming the conservation law is still valid, then where does the energy come from?

The momentum of falling water is created by gravity. If science asked only questions with inheremt answers we would know much less.

I have hinted at the answer, but obviously no one has a clue. Please let me say this. Classical physics has its value and its place, but the great achievement of Sir Isaac Newton has been superseded by the great achievement of Doctor Albert Einstein. IF you really want to know how the universe works study Relativity.

Here is another hint: From where does atomic energy come from? It does not come from another form of energy as such. In something like this gravity does not come from another different energy source, but from something else, which can be and is converted to energy, just as matter can be converted to energy.

I plan to post the accepted answer soon to the Conservation Law question I raised, and will then post another question closer to classical physics. The question I will post is one of those on Advertising removed and relates to underground hydrostatics on the Moon. It should be much easier to answer.

Best regards,

Phillip Duke PhD

It is disappointing to me that you students of classical physics have never studied Relativity, why is that? Don't you know that Einstein's work invalidates that of Newton?

Edited by hypervalent_iodine

##### Share on other sites

Don't you know that Einstein's work invalidates that of Newton?

Not true.

I was curious to hear your explanation but my curiosity is slowly being replaced by indifference; I've never been much for bloviation.

##### Share on other sites

Introducing tidal energy generation has somewhat side tracked the question,

With the greatest respect you introduced it.

Further you did not address my post#12, contrary to the rules of this forum.

Since the "force of gravity" can be employed to do work and generate electrical energy, and assuming the conservation law is still valid, then where does the energy come from?

The energy is supplied by the other agent that must act in order for work do be done.

Gravity, (or any other force) cannot do work by itself.

##### Share on other sites
This topic is now closed to further replies.

×