Where does potential energy come from?

[Tumorsito]

Lets suppose we put a point particle with a mass m here on earth. No energy was used to put it there. It makes sense it will go down, but where does gravity gets the energy to pull the particle? from the earth/particle mass?

 

[DrStupid]

but where does gravity gets the energy to pull the particle?

It doesn't need to get it. The potential energy will just decrease, no matter if ther was potential energy before or not or if you even start with negative potential energy.

 

[Drakkith]

Energy is the result of forces acting on systems of objects, not the other way around.

 

[gmax137]

Here is what I think is one of the best lectures on energy. Worth reading a few times over.

http://www.feynmanlectures.caltech.edu/I_04.html

 

[Tumorsito]

Energy is the result of forces acting on systems of objects, not the other way around.

since we put our mass, there is a force on the system that will attract the 2 particles. This force needs to do a work to move the particles, if I am right until this point, energy must come from somewhere?

 

[Drakkith]

since we put our mass, there is a force on the system that will attract the 2 particles. This force needs to do a work to move the particles, if I am right until this point, energy must come from somewhere?

In your question this is basically not answerable since you've already broken the laws of physics by placing a mass at a point in a gravitational field without performing any work. In the real world energy is conserved, so there is never a question about where it comes from or what's happening to it.

 

[Tumorsito]

In your question this is basically not answerable since you've already broken the laws of physics by placing a mass at a point in a gravitational field without performing any work. In the real world energy is conserved, so there is never a question about where it comes from or what's happening to it.

If placing a mass needs a work to be putted, who was the first mass putted? (i know its an unanswerable question and a more phylosophycal one). However let's suppose we can summon a couple of particles for a little amount of time (like in heisemberg principle, i don't want to extend further more bc i don't have the knowledge needed to be right on what I am saying, at this point i don't actually know if what i say its right), this two particles will create a gravitational/electrostatic field and will atract the other particle, where does this energy comes from?

 

[Bandersnatch]

In your question this is basically not answerable since you've already broken the laws of physics by placing a mass at a point in a gravitational field without performing any work.

I don't think that's a problem. You can set up the system however you like, before analysing its further behaviour.

since we put our mass, there is a force on the system that will attract the 2 particles. This force needs to do a work to move the particles, if I am right until this point, energy must come from somewhere?

Look at the equation for potential energy. The variable is position. Hence, it comes from the position of masses in gravitational fields.

 

[DrStupid]

you've already broken the laws of physics by placing a mass at a point in a gravitational field without performing any work.

That depends on where the particle comes from. You don't need to read the original post in the worst possible way.

this two particles will create a gravitational/electrostatic field and will atract the other particle, where does this energy comes from?

It is a matter of definition if the potential energy is positive, negative or zero. With the usual convention for the gravitational potential energy (zero in infinite distance) you already start with negative potential energy and it becomes even more negative if the particles accelerate toward each other.

 

[Drakkith]

I don't think that's a problem. You can set up the system however you like, before analysing its further behaviour.

Sure, if you're asking what the potential energy of the mass is. But asking where did the energy come from seemed to me to be a different kind of question. One that would require knowledge of the history of the mass and what actions had been done to it.

If placing a mass needs a work to be putted, who was the first mass putted? (i know its an unanswerable question and a more phylosophycal one). However let's suppose we can summon a couple of particles for a little amount of time (like in heisemberg principle, i don't want to extend further more bc i don't have the knowledge needed to be right on what I am saying, at this point i don't actually know if what i say its right), this two particles will create a gravitational/electrostatic field and will atract the other particle, where does this energy comes from?

Potential energy comes from the forces between a system of objects combined with the particular arrangement of those objects. So if system A is in a particular configuration then you can say that it has X amount of potential energy. Note that these forces don't require energy to function. Like I already said, energy comes from forces acting on objects, forces do not come from energy. So if you set up a system such as the one in your original question, there's no problem is asking how much potential energy a mass has. But, as I just explained to Bandersnatch, I interpreted your question to be one in which you were asking about a system with no test mass suddenly transitioning into a system with a test mass, with no physical mechanism to put that mass there, and wanting to know where the extra potential energy came from.

I hope that makes sense.

 

[Dale]

if I am right until this point, energy must come from somewhere?

It comes from the gravitational field

 

[Herman Trivilino]

this two particles will create a gravitational/electrostatic field and will atract the other particle, where does this energy comes from?

It came from whoever it was who put those particles there!

Energy is a property of that system. When you create the system you create the energy.

 

[Neeraj Chandran]

Lets suppose we put a point particle with a mass m here on earth. No energy was used to put it there. It makes sense it will go down, but where does gravity gets the energy to pull the particle? from the earth/particle mass?

According to Newton every mass attract each other. For me I go with Einstein s theory, mass is a form of energy and it can bend the space time and as a result every object should get attracted to earth. As there is a force pulling the object downwards, a work should be done to escape or move a particle against the direction of motion, and according to work energy concept, energy is conserved and the energy that is spend to do the work is now stored in that particle. So when gravity acts on it, the gravity persuades it to convert the potential energy to kinetic energy and it falls in the direction of force