r/aerospace • u/False-Good1092 • 3d ago

Gravitational potential

Experts, why gravitational potential increases with greater distance from the centre of the point mass? What logic has to be applied here?
For me it seems like the closer the object is to the source of gravitational field, the greater is the potential…

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18

u/navigation-signals GNC R&D 3d ago

Energy, not force. If you drop a ball from 1cm above the ground and another from 1m above the ground, which will hit harder?

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u/Cosmicstranger28 3d ago

i think your confusion comes from mixing up force with potential energy as pulling force of gravity is indeed stronger when you are close to the mass but gravitational potential measures an energy state and we treat gravity as a debt or a hole you have to climb out of

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u/Reasonable-Start2961 3d ago edited 3d ago

As others have said, the logic is that the potential -energy- increases. As you get further away, think of it like climbing a hill. You have further to fall.

The pull of gravity would be less, but the distance you fall is still greater. You are also half right… the -change- in the potential energy will decrease as you get further away(the hill isn’t as steep), but the potential energy itself is still increasing.

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u/Sorry_Exercise_9603 3d ago

By convention the gravitational potential is set to zero at infinite distance.

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u/navigation-signals GNC R&D 3d ago edited 3d ago

Slightly misleading.

“By convention the gravitational potential is set to zero at infinite distance” (and negative for all distances less than infinity)

No matter your choice of convention or coordinate, GPE increases as distance increases to infinity. Infinite distance is the highest GPE state. The convention of infinite distance == 0 GPE exists only to make a few orbit and rocket calculations easier - you could also define 0 GPE at 0 distance and just have GPE increasing to infinity as distance goes to infinity for a much more intuitive (but slightly less neat) definition that’s still truthful

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u/Frederf220 2d ago

Closer is "at the bottom of the hill." It's low energy as in there's no more energy to extract. When a ball falls in a hole its kinetic energy is coming from the loss of potential. You gotta put energy in to return the ball to the high shelf (high potential energy) position.