You need energy to produce a force that compensates gravity. So if you apply that force for a huge amount of time, will gravity ever be depleted?
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Forces (gravity, electromagnetism, the strong and weak forces) don’t consume energy but can move stuff around and keep them in place. The universe is weird like that.
As others said, gravity does not “run out”.
Also, you only use energy to move things. A rock laying on the ground is not using any energy. Lifting the rock up will require energy.
Keeping the rock up with a jet engine does use energy, but you use that energy to make air act like a solid pillar supporting the rock.
If you keep sending rocks into space, you will reduce mass of the earth and hence its gravity. But you will achieve same thing by throwing rocks into a portal to another dimension, so it’s not like you are using up gravity.
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It depends what you mean. For example 2 co-orbiting blackholes emit gravitational waves. This loss of energy causes the 2 blackholes to eventually fall towards each other and merge.
Since most of the answers refer to gravity in the way it is perceived on Earth, here’s another question:
Moon’s gravitational pull is creating tides on Earth. Those tidal moves can be converted into energy. If we assume that water will always exist on Earth, we could say that gravity is a perpetual source of energy. Or is it?
No, force is not equal energy, if there’re forces but nothing happens then there’s no energy. A book on a table has forces acting on it, but it doesn’t move so no work has been done. To make gravity do work(work is basically energy btw.) things have to fall(otherwise it would just be a book sitting on a table), like a book falling from the table or water flowing from higher elevation(pass it through a generator, and you get a hydroelectric dam) but for book to fall off the table, someone must put it up there which require energy, as for water, it’s the sun that do the work by driving water cycle…basically you can’t get free energy from gravity, gravity is not a generator, it’s a BATTERY, it doesn’t create energy, it stores energy in form of height, the higher you put a thing the more energy that thing has, which you can extract by making it fall, if the thing doesn’t fall then there’s no work and you can’t get work done without something doing the work.
The more you use it, the more the object comes closer to reaching the ground thats why it is limited
The water flowing though a huge hydroelectric damn creates energy .. .. where does this energy come from? Is it endless?
It cannot work as endless energy. Gravity works more like a battery that can store kinetic energy. Very similar to a spring; you load an object at some height (store the energy) then as you release the object you get kinetic energy.
Gravity can store energy, but it cannot be a source.
So in order for a book to rest on a table and not move relative to the Earth, the table needs to exert a force on this book. It’s called the normal force. Where is this energy coming from that this table is exerting on the book?
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