Exploring the Role of Gravity in Energy Production: A Thought-Provoking Inquiry

In summary,The energy needed to raise the water vapour is mgh where m is the mass of water, g the acceleration due to gravity an h Is the height. This energy is provided by the sun. Once the water vapour is up there it has potential energy also equal to mgh. As the water droplet falls the potential energy is converted to kinetic energy.
  • #1
Gaurav Samanta
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1
Hi everyone! I'm here for a little conveyance towards a question that is disturbing me for days.

Just suppose, you and I design a hydroelectric generator that provokes energy from the downflow of precipitating rain. These falling drops of rain surely have originated from the vapours of the ocean and no doubt it is the Sun who has provided the Potential energy to the vapours to go up. These vapours then formed clouds which thereafter changed into rain droplets. These rain droplets then made their way down and of course, it is the invisible Gravity which brought them down by providing them Kinetic energy.

So, the condition arises is if the accomplished energy of our generator is the outcome of the Kinetic energy provided by Gravity, where has the energy of the Sun gone; and in contrast, if the potential energy of the Sun rays transformed into kinetic energy then why is Gravity required?

My teacher answered, "Gravity is just a force, not a donor of Kinetic energy." Then the question that can be further asked is — "A heavy ball placed on a thin plastic sheet conclusively breaks the sheet after some while. For that to happen there must have been a constant supplier of Kinetic Energy for all the plastic bonds to break. If Gravity is not the perfect provider then what it is?"
 
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  • #2
Gaurav Samanta said:
... if the accomplished energy of our generator is the outcome of the Kinetic energy provided by Gravity, where has the energy of the Sun gone...
Into whatever the generator powers.

Gaurav Samanta said:
... why is Gravity required?
It isn't in general. See solar cells.

Gaurav Samanta said:
My teacher answered, "Gravity is just a force, not a donor of Kinetic energy."
It is a conservative field.
 
  • #3
I would really appreciate if you can provide me with the equations for what you are replying!
 
  • #4
You can start at the sun:
1) The photons from the sun's nuclear processes travels to Earth as they exit the sun's gravity well they lose some small amount of energy.
2) The Sun's photons travel to Earth and agitate the water molecules by colliding with them causing them to move faster (ie heat the water)
3) The water molecules escape from the water surface rising into the air and continue to collide with photons and other molecules
4) As the molecules rise, they gain potential energy and they begin to coalesce into water droplets and then fall to Earth
5) As they fall, they convert their potential energy back into kinetic energy.
6) As they fall on your generator they cause it to rotate and to thus generate electricity
7) During this conversion the generator dissipates some of the energy into heat and the rest into electrical energy to power devices.

You have to remember the potential energy sources are like stretched springs, gravity converts kinetic energy of movement into potential energy of no movement. Same goes for a capacitor, storing electric charge up until released by making a circuit for the electric charge to move.
 
  • #5
Gaurav Samanta said:
I would really appreciate if you can provide me with the equations for what you are replying!

Okay, but you didn't ask with equations. You asked with concepts and so that's how we answered.
 
  • #6
jedishrfu said:
1) The photons from the sun's nuclear processes travel to Earth as they exit the sun's gravity well they lose some small amount of energy.

Firstly, they are reluctant to lose energy. Photons have no mass, thus are unaffected by Gravity

jedishrfu said:
5) As they fall, they convert their potential energy back into kinetic energy.

Concluding this, I asked Why is Gravity required? Do you want to show me Gravity as an Energy transformer?
 
  • #7
Gaurav Samanta said:
Firstly, they are reluctant to lose energy. Photons have no mass, thus are unaffected by Gravity.
This is not correct. Despite not having mass, photons are affected by gravity in two ways:

1. A photon moving outward from a gravitating object is red-shifted and similarly, a photon moving inward toward a gravitating object is blue-shifted.
2. A photon passing a gravitating object is deflected due to the curvature of space-time.

Concluding this, I asked Why is Gravity required? Do you want to show me Gravity as an Energy transformer?
A car rolling down a hill and crashing into a building is an example of gravity as an energy transformer.

If you mean to ask: "why is gravity required to convert solar energy into electricity" then that has already been answered by @A.T. It is not required.
 
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  • #8
Some equations...

The energy needed to raise the water vapour is mgh where m is the mass of water, g the acceleration due to gravity an h Is the height. This energy is provided by the sun.

Once the water vapour is up there it has potential energy also equal to mgh.

As the water droplet falls the potential energy is converted to kinetic energy. For the moment we will assume that all of the potential energy is converted to kinetic energy so the kinetic energy the water gains as it falls is also equal to mgh.

So in summary the energy in the falling water is exactly the same as the energy provided by the sun. In practice it's less because some energy is lost to friction with the air as the water falls etc.

So gravity was only a temporary store for the sun's energy, not a source of energy.
 
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  • #9
You might also care to Google conservative forces. Gravity is a conservative force so if you move something around a closed path the net work done is zero. Eg the energy needed to raise something up is exactly the same as the energy you get back on the way down. So the net sum is zero.
 
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  • #10
That's what I needed. I can now draw a whole conclusion.

Gravity is a conservative field. The sun was the donor of energy and its rays transformed water into vapour. If I see this whole along with the concept of Latent Heat, everything becomes clear. The change in the height of vapour and the transportation of energy was just The Play of Gravity.

Thanks CWatters, jbriggs444, jedishrfu, and AT
 
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  • #11
Gaurav Samanta said:
I would really appreciate if you can provide me with the equations for what you are replying!
This link seems to be pretty comprehensive, if you want a load of equations.
 
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  • #12
Gaurav Samanta said:
I asked Why is Gravity required?
You started with:
Gaurav Samanta said:
you and I design a hydroelectric generator
Gravity is therefore required because you decided to discuss the operation of a device which is specifically designed to extract energy from a fluid due to a change in the gravitational PE of the fluid.

Nature didn’t force us to use a hydroelectric generator, you chose it.
 

1. What is the play of gravity?

The play of gravity refers to the force of attraction between two objects with mass. It is a fundamental force in the universe and is responsible for keeping planets in orbit around the sun and objects on Earth from floating off into space.

2. How does gravity work?

Gravity works by pulling objects towards each other based on their masses and the distance between them. The larger the mass of an object, the stronger its gravitational pull. This force decreases as the distance between objects increases.

3. Who discovered gravity?

The concept of gravity has been studied and theorized by many scientists throughout history, but it was Sir Isaac Newton who is credited with discovering the laws of gravity in the late 17th century. His famous law of universal gravitation states that every object in the universe attracts every other object with a force proportional to their masses and inversely proportional to the square of the distance between them.

4. How does gravity affect the motion of objects?

Gravity affects the motion of objects by constantly pulling them towards the center of the Earth. This force is responsible for objects falling towards the ground when dropped and for keeping objects in orbit around the Earth. Without gravity, objects would continue to move in a straight line at a constant speed.

5. Can gravity be manipulated or controlled?

Currently, there is no known way to manipulate or control gravity. It is a fundamental force of nature and is not affected by human actions. However, scientists are constantly researching and studying the properties of gravity in hopes of one day being able to manipulate it for practical purposes.

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