Is there Gravitational Potential Energy on a horizontal surface?

[freshbox]

Is there Gravitational Potential Energy on a horizontal surface?

Example from Position 1 - 2

 

[Doc Al]

Since the height doesn't change, there's no change in gravitational PE. (Which is what matters.)

 

[freshbox]

So GPE=0?

My understanding is that if there is height, there is GPE.

 

[Doc Al]

So GPE=0?

My understanding is that if there is height, there is GPE.

Depending on the reference point you choose, which is arbitrary, there may be non-zero GPE. But what really matters physically is the change in GPE, which in this case is zero. ΔGPE = 0.

 

[CWatters]

If there is gravitational PE at point one (due to it's height above a reference that is not shown on the drawing), and point two is the same height above that reference, then the gravitational PE is the same at both points.

 

[freshbox]

Thanks for the explanation.