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Miraj Kayastha
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is GPE at a point the work we must do against the gravitational force to bring an object from infinity to the point? Or is it the work done by the gravitational force?
Yes.Miraj Kayastha said:is GPE at a point the work we must do against the gravitational force to bring an object from infinity to the point?
No, it's the negative of that.Or is it the work done by the gravitational force?
Miraj Kayastha said:is GPE at a point the work we must do against the gravitational force to bring an object from infinity to the point? Or is it the work done by the gravitational force?
sophiecentaur said:It has to be the work done ON. The Force could be due to many causes - a spring and gravity, for instance. How would you apportion the work done BY between the two, if it worked your alternative way? If you read the definition anywhere, it is quite consistent.
jbriggs444 said:What point are you trying to make here? That gravitational potential energy is equal to the work done ON an object to oppose gravity rather than the work done ON an object by gravity amounts to nothing more than a sign convention.
We adopt the sign convention that we do so that "Kinetic Energy" plus "Gravitational Potential Energy" is conserved.
One could equally well adopt the opposite sign convention so that "Kinetic Energy" minus "Gravitational Energy Deficit" is conserved.
sophiecentaur said:I was just pointing out that using the definition avoids any confusion (of sign, as you say). If you start introducing the idea that gravity 'does work' when things fall then there can be utter confusion if and when there is another agency involved. I think that is a valid point and is not just a matter of a sign.
Miraj Kayastha said:is GPE at a point the work we must do against the gravitational force to bring an object from infinity to the point? Or is it the work done by the gravitational force?
jbriggs444 said:If gravity is modeled as a force then gravity does do work when things fall. If two forces are applied to a moving object then both forces do work. That there can be confusion does not change the facts of the matter.
sophiecentaur said:The question was about Gravitational Potential. I thought that was defined in terms of Work done ON a unit Mass to bring it from infinity. Isn't that the fact of the matter? I can't see a need to consider who does the work so why is there a need to worry further?
Gravitational potential energy is the energy that an object possesses due to its position in a gravitational field. It is the potential to do work by virtue of an object's position relative to other objects.
The formula for calculating gravitational potential energy is GPE = mgh, where m is the mass of the object, g is the acceleration due to gravity, and h is the height or distance from the reference point.
The reference point for calculating gravitational potential energy is usually chosen to be at the surface of the Earth, where the gravitational potential energy is considered to be zero. However, it can also be chosen at any point where the potential energy is known or can be easily calculated.
Gravitational potential energy is directly proportional to the height or distance from the reference point. As an object moves farther away from the reference point, its gravitational potential energy increases. Conversely, as it moves closer to the reference point, its gravitational potential energy decreases.
The greater the mass of an object, the greater its gravitational potential energy. This means that two objects situated at the same height will have different gravitational potential energies if they have different masses. However, the gravitational potential energy per unit mass will be the same for both objects.