Spring Potential Energy
Spring Potential Energy
Say a dissolvable spring is compressed with a bolt and nut that do not melt in a sulfuric acid solution. The spring has quite a bit of potential energy at this point since it is compressed. Assuming the spring dissolves perfectly (no breakage, just complete disintegration), what happens to the potential energy of the spring?
Assuming the spring dissolves perfectly (no breakage, just complete disintegration)
I think, eventually, this assumption breaks down. As the metal is dissolved away, the internal stresses in the spring will become greater than the remaining metal can hold, and the spring will break.
If the spring does eventually break, it will be a weaker spring since a lot of material is gone. The potential energy of a spring at the breaking point would be different than the original spring. So I guess I could rephrase the question, what happens until that point? Does it get let go as heat?
Fair enough, thinking about it at a microscopic level, individual molecules/atoms of material will be pushed into positions where they are being repelled from other atoms/molecules via electromagnetic forces. Those forces won't go away as the chemical reactions happen; so, I would guess that the answer is kinda the same as it is at the macroscopic level. When the bond which holds an individual atom in the lattice of the material is broken, those electromagnetic forces would push the resulting molecule away. So ya, it becomes heat.
Layman's conjecture: as the spring dissolves, the sulfuric acid's temperature would rise.
That's one hell of an assumption. It's not gonna break down equally across the entire spring. Whatever the weakest point is will eventually wear away first and cause it to break because of all the tension in it.
Even if it could dissolve equally across the entire spring, the outer parts would go first and it eventually will dissolve away from the things holding it in place and release that tension. If it doesn't just break due to the dissolving metal weakening the structure while still under tension.
I feel like to get the meat and potatoes of the question a better way of asking would be what would happen to the potential energy if the spring was instantly vaporized, like by a Star Trek phaser.
I think it would be same answer really.
I would imagine that as the tiny bits of the spring are released from one another, the stored energy would be released as a small force within the acid. That is, even if the reaction was perfect down to the molecular level, the new molecule combination would be "launched" away from the spring more vigorously than if the spring weren't compressed. So you'd end up with the acid being "stirred" a bit by the reaction.
I’m just trying to visualize this, it’d be similar when you break something in half and a tiny piece goes flying
Yes Ik very different concepts but I’m just trying to make visual brain happy here
Yeah, kinda like breaking a handful of dry spaghetti (sorry Italians).
The potential energy of the spring is “stored” in individual molecules that are pushed into some configuration that they don’t quite want to be in, and they exert force on each other trying to push themselves back apart / back together into being the way they like. As the spring disintegrates, you could model those individual forces, and molecules exerting force on each other would release it into kinetic energy one by one or in groups, as the spring gradually lost its integrity to exist as a singular entity.
(I think that in practice, metals are made of grains, big groupings of molecules which stay pretty much as rigid bodies unless something really crazy happens, so most of the potential energy is force of the grains wanting to go back into their preferred arrangement in relation to other grains. I.e. not in practice at the level of molecule to molecule. But I’m not 100% on that part.)