Is there proof gravity can not be a energy source?

[utilitarian]

No, like I said, no self-sustaining machine can be made out of this. But not being able to make a self-sustaining machine is not a criterion for whether or not CoE can be violated. CoE in this case is violated because the integral of the work done in a closed loop is not zero as it should be if CoE is obeyed. And, no, in this case potential energy is not converted into kinetic on its way up. The kinetic energy at the top of the hill is in addition to the potential energy the car has there. So at the top of the hill the car has (potential energy + kinetic energy1) while at the bottom of the hill, when the car returns spontaneously that potential energy only is converted into potential energy2. So as far as the car is concerned we have: potential energy = kinetic energy2 < (potential energy + kinetic energy1). CoE is violated. If CoE were not violated we would have potential energy = kinetic energy2 = (potential energy + kinetic energy1) which is not the case.

I just have to say, this is the biggest bunch of nonsense I have ever seen from a thinking person.

However the car gets up the hill initially, whether by push or by gasoline, that kinetic energy is traded for potential.  Then, as the car begins to slide back down the hill, it has very little kinetic, still lots of potential energy.  As it rolls down, it trades potential for kinetic, and assuming zero friction, will end up on top the second hill with zero kinetic and the exact same amount of potential it had when it started on the first hill.

Every bit of energy is accounted for and there is nothing extra.  If there was extra energy, then we could have a self sustaining apparatus out of this, but alas no.  Tell me where the extra energy is?  It is nowhere there.

[Omnibus]

I just have to say, this is the biggest bunch of nonsense I have ever seen from a thinking person.

However the car gets up the hill initially, whether by push or by gasoline, that kinetic energy is traded for potential.  Then, as the car begins to slide back down the hill, it has very little kinetic, still lots of potential energy.  As it rolls down, it trades potential for kinetic, and assuming zero friction, will end up on top the second hill with zero kinetic and the exact same amount of potential it had when it started on the first hill.

Every bit of energy is accounted for and there is nothing extra.  If there was extra energy, then we could have a self sustaining apparatus out of this, but alas no.  Tell me where the extra energy is?  It is nowhere there.

You should restrain from qualifications, especially when you're writing utter nonsense such as the above.

A car can get to the top of the hill very slowly or it can get to the top of the hill at a very high speed. An object of a given mass at the top of the hill has only a strictly given gravitational potential energy. That object can have at the top of the hill different kinetic energy, depending on how it got there. Therefore, in now way is the potential energy (a given) traded for the kinetic energy the body has at the top of the hill. Furthermore, the body can be brought up to the top of the hill at such a speed that its potential energy there will be negligible cpmpared to its kinetic energy. Like I said, the kinetic energy the body has at the top of the hill (having nothing to do with the potential energy that bodyhas at the top of the hill) is different from the kinetic energy the body has at the foot of the hill, exchanged for its potential energy when it slid spontaneously down the hill.

[utilitarian]

You should restrain from qualifications, especially when you're writing utter nonsense such as the above.

A car can get to the top of the hill very slowly or it can get to the top of the hill at a very high speed. An object of a given mass at the top of the hill has only a strictly given gravitational potential energy. That object can have at the top of the hill different kinetic energy, depending on how it got there. Therefore, in now way is the potential energy (a given) traded for the kinetic energy the body has at the top of the hill. Furthermore, the body can be brought up to the top of the hill at such a speed that its potential energy there will be negligible cpmpared to its kinetic energy. Like I said, the kinetic energy the body has at the top of the hill (having nothing to do with the potential energy that bodyhas at the top of the hill) is different from the kinetic energy the body has at the foot of the hill, exchanged for its potential energy when it slid spontaneously down the hill.

Maybe I should not have used that term, but I just don't see it.  I will try to be more civil.  But based on your logic, even a pendulum would violate the CoE principle.  Yet we can observe a low friction pendulum swinging for a long time, eventually stopping due to friction losses.

How is energy not conserved?  All pendulums eventually stop, so there is certainly no extra energy, not even a tiny amount required to overcome the little friction there is.

Or are you saying that CoE is violated the other way, that more energy is lost than can be accounted for?

[Omnibus]

Correct. If you have a pendulum at equilibrium and deflect its bob to a certain height h, the kinetic energy you have imparted to the bob (which will be a different kinetic energy than the kinetic energy due to the transformation, after letting the bob go, of the potential energy the bob has at h) will not be restored after letting it go until reaching equilibrium. Thus, the pendulum will also violate CoE -- the closed loop integral of force over displacement (work) will not be zero.

[spinn_MP]

Correct. If you have a pendulum at equilibrium and deflect its bob to a certain height h, the kinetic energy you have imparted to the bob (which will be a different kinetic energy than the kinetic energy due to the transformation, after letting the bob go, of the potential energy the bob has at h) will not be restored after letting it go until reaching equilibrium. Thus, the pendulum will also violate CoE -- the closed loop integral of force over displacement (work) will not be zero.

Unbelievable... This OmniBot hyperproductive idiot is still preaching his eternal super delusional lying mantra, even if it's quite obvious that he doesn't have the slightest idea what potential or kinetic energy actually is...
Disgusting.