potential energy is. IMO, largely a pedagogical tool. it's an explanatory position, rather than a thing.
the rock, does, obviously "contain" energy thanks to e=mc2. but the notion that the rock is energetically in a different state as it sits on top of the mountain that when it sits at the bottom never sat well with me in high school, and it still doesn't, 45 years later.
It takes energy to move a rock to the top of a mountain, and you can get some of that energy back (minus friction etc) if you let it roll down. So it's got something.
I mean any type of energy is just as intangible as potential energy, so I don't see that the energy stored by doing work (i.e. interacting with one four forces) is that different to the idea of energy stored by being in motion. You never measure "energy" directly after all, but it's a useful abstraction - after all, everything in science is an explanatory position.
Yes, everything in an explanatory position. That's precisely the point I was trying to get to.
I just happen to consider the explanation that a rock sitting on top of a mountain having "potential energy" to be relatively content free.
There's always a tension in physics (or has been for a couple of centuries or so) between force-based explanation and energy-based explanation.The force-based explanation (gravity) of why the rock might move downhill makes vastly more sense to me than the notion that it has "potential energy". However, the force-based explanation is not always clearly the right one either.
Also, I wasn't referring to "the idea of energy stored by being in motion". This is precisely the hangup that trips up so many. An object doesn't have energy because it is moving. And it doesn't move because it has energy. The motion and the energy are the same thing, just two different ways of talking about the same thing. The distinction matters because the way we've developed the semantics of "motion" and "energy" in physics means that, for example, "motion" is not something that is transferred between objects, but "energy" is.
the rock, does, obviously "contain" energy thanks to e=mc2. but the notion that the rock is energetically in a different state as it sits on top of the mountain that when it sits at the bottom never sat well with me in high school, and it still doesn't, 45 years later.