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Old 01-12-2018, 03:02 PM
  #21  
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Originally Posted by Wood boat builder View Post
The water had potential energy when it was held behind the dam.

When the gates opened and let the water start moving the potential energy was converted into kinetic energy.

The turbine Took some of the kinetic energy from the moving water and turned it into mechanical energy that turned a generator.


The water Downstream of the dam is still has some energy and is moving through the riverbed.

There is friction between the moving water and the riverbed and some of the kinetic energy is being transformed into heat.
What part of what I said are you disagreeing with?
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Old 01-12-2018, 03:36 PM
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H=v^2/2g
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Old 01-12-2018, 06:34 PM
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Fwiw-
Torquing up bolts w/2-1/2" drive 9-1/2" AF socket-Water wheel(turbine) Niagara Moses power dam.
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Old 01-12-2018, 07:48 PM
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My head hurts after reading some of these replies
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Old 01-12-2018, 09:49 PM
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The plane will take off.
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Old 01-13-2018, 12:06 AM
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The water in the stream is all easy to figure.

Five years ago I stuck a magnet on the metal ceiling grid at the office. It takes energy to keep it from falling to the floor. I haven’t filled the gas tank on the magnet in five years but the damn things still stuck there with the same apparent pull-off force it always had. How does it manage to defy gravity seemingly without running out of energy?
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Old 01-13-2018, 12:12 AM
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Originally Posted by nccoaster View Post
The plane will take off.
Absolutely! Well, unless the catastrophic failure of the wheel bearings results in a horrific crash first.
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Old 01-13-2018, 01:18 AM
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Yes my head hurts now as well.

Yet another concept to the equation is pumped storage. Energy from an upper reservoir flowing through turbines to make electricity then flowing to the pump storage reservoir during higher load demands.

During low load demands on nights and weekends, this same water is pumped back up to the upper reservoir to be reused again so the energy from the larger base load units can be absorbed to keep from cycling large steam turbines.

https://illumination.duke-energy.com...untain-4608936

https://www.duke-energy.com/energy-e...385.1515834243




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Old 01-13-2018, 02:09 AM
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Originally Posted by Fish Haid View Post
Water behind a dam flows out the bottom under pressure and powers a turbine generator to produce electricity. This can be used to create heat. Water then flows to the ocean eventually.

So, the water at high altitude has stored potential energy. Some of which is extracted as electricity. Eventually the water reached sea level and has zero potential energy.

Now, compare to water flowing without the restriction of the damn and generator. It too eventually reaches sea level and has zero potential energy. Where did the original energy go? Does water heat up as it flows to the ocean? Does the generator cool the water?
Potential energy from pressure/flow and water temperature are two separate things.

The water held behind a dam has potential to create energy just as the unimpeded water with no dam. You don’t need a dam to derive energy from water flow, but it is the most efficient way of doing so.

Regarding heating or cooling, it depends on the environment. If you have a high altitude pond, the water will be warmed by solar energy, then be cooled as it makes its way down a mountainside by evaporation. The same stream, fed by a spring will warm as it makes its way to the sea.

I beg to differ on zero potential energy at sea level. That water is part of the water cycle. Through evaporation, the sea water eventually makes its way back to a place where it has better potential energy.

Long and short, water, no matter where it resides, never loses its potential energy.
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Old 01-13-2018, 03:35 AM
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Originally Posted by Lone Ono View Post
The water in the stream is all easy to figure.

Five years ago I stuck a magnet on the metal ceiling grid at the office. It takes energy to keep it from falling to the floor. I haven’t filled the gas tank on the magnet in five years but the damn things still stuck there with the same apparent pull-off force it always had. How does it manage to defy gravity seemingly without running out of energy?
Does the metal ceiling grid fall on your head when it runs out of energy?

Energy is the capacity for doing work. Work (W) is the product of force (F) times distance (d), or W= F x d. If the magnet is not moving, d=0, so it is not doing any work and therefore it is not consuming any energy.
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Old 01-13-2018, 06:31 AM
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So you can hang with your chin above the bar indefinitely as long as you stay completely still? Gravity has no effect on you because you are motionless? No force is exerted against the dam by the water as long as there’s no boats stirring up a wake?
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Old 01-13-2018, 07:16 AM
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Originally Posted by Lone Ono View Post
So you can hang with your chin above the bar indefinitely as long as you stay completely still? Gravity has no effect on you because you are motionless? No force is exerted against the dam by the water as long as there’s no boats stirring up a wake?
What does that have to do with anything?
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Old 01-13-2018, 07:35 AM
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Originally Posted by Lone Ono View Post
Absolutely! Well, unless the catastrophic failure of the wheel bearings results in a horrific crash first.
It's more likely that the treadmill will explode.
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Old 01-13-2018, 07:46 AM
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Originally Posted by Lone Ono View Post
Absolutely! Well, unless the catastrophic failure of the wheel bearings results in a horrific crash first.
Will it crash into the dam? Where does all THAT energy go?
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Old 01-13-2018, 07:51 AM
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Originally Posted by yarcraft91 View Post
Does the metal ceiling grid fall on your head when it runs out of energy?

Energy is the capacity for doing work. Work (W) is the product of force (F) times distance (d), or W= F x d. If the magnet is not moving, d=0, so it is not doing any work and therefore it is not consuming any energy.
Further, work is heat. If the magnet gets warm, it's "working". It's just applying a force counteracting another force..gravity. No work=no heat=no MOVEMENT!
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Old 01-13-2018, 08:16 AM
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Nuclear energy is the answer, leave the fricken stream alone.
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Old 01-13-2018, 08:19 AM
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Originally Posted by txj33p View Post
Nuclear energy is the answer, leave the fricken stream alone.
True. The only real source of energy. No mass change, you are not creating new energy, just releasing stored energy.
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Old 01-13-2018, 10:07 AM
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In really simple terms, the water itself does not have energy (kind of) by virtue of the fact that it is elevated, gives it potential energy, from gravity, once it is at sea/lake level, it no longer has potential, but gravity is still in place, so in a simple way, the potential was removed.
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Old 01-13-2018, 11:05 AM
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Originally Posted by noelm View Post
In really simple terms, the water itself does not have energy (kind of) by virtue of the fact that it is elevated, gives it potential energy, from gravity, once it is at sea/lake level, it no longer has potential, but gravity is still in place, so in a simple way, the potential was removed.
Energy was put into the water by raising it to the height of the lake. This energy is relaesed as it falls. Gravity is a force..movement against a force is work.
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Old 01-13-2018, 12:48 PM
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Simple,

Entropy always increases
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