Is there Gravitational Potential Energy on a horizontal surface?
Example from Position 1 - 2
Since the height doesn't change, there's no change in gravitational PE. (Which is what matters.)
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.
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.
Thanks for the explanation.
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