# Gravitational energy

• June 26th, 2008, 02:39 PM
NeptuneCircle
Gravitational energy
Alright, can someone please explain this to me. The first law of thermodynamics states that energy can not be created nor destroyed. However gravity seems to apply 'unlimited amount' of energy in the sense that of an object falls, and there are no forces acted against it, it will continue to accelerate.

In fact, I don't even understand the relationship between force and energy. If a constant force is applied to an object it will continue to accelerate and at the same time have more and more kinetic energy, yet where is this energy coming from?
• June 26th, 2008, 03:37 PM
Bactrian18
Re: Gravitational energy
Quote:

Originally Posted by NeptuneCircle
Alright, can someone please explain this to me. The first law of thermodynamics states that energy can not be created nor destroyed. However gravity seems to apply 'unlimited amount' of energy in the sense that of an object falls, and there are no forces acted against it, it will continue to accelerate.

In fact, I don't even understand the relationship between force and energy. If a constant force is applied to an object it will continue to accelerate and at the same time have more and more kinetic energy, yet where is this energy coming from?

For an object to "fall" first it has to be "lifted"(ie energy has to be transferred/work has to be done). This work is equal to the work gravity might do to pull it back down. And you might ask what about the objects that are there from the begining? Were they also "lifted"? Yes. By The Big Bang.
As to your second question, it could just be a case of change of the form of energy. Like if your muscles are causing the object to move, then the source of energy are the molecules being burnt by your body. Or if the cause of the difference in speed of the object was another moving object hitting it, then it's just a case of transferring kinetic energy from one objec to another...
• June 26th, 2008, 04:12 PM
NeptuneCircle
alright thanks. I guess that answers my question.