The problem with this interpretation is that it relies on hyper-literal RAW when it's convenient and physics when it's convenient. If you apply the rules of physics to the wooden rod, then the answer is simple: the peasant railgun cannot make the rod travel several miles in 6 seconds. If you apply D&D RAW, the rod can travel infinitely far, but does not have momentum and doesn't do anything when it reaches its destination. You only get the silly result when you apply RAW to one part of it and ignore it for another part.
Yep. And if we apply hyper-literal RAW rules, then gravity also doesn't accelerate items, it simply sets their velocity to some arbitrary degree. None of the falling rules I've seen have ever mentioned acceleration, only fall speed.
(Actually, it looks like it's Sage Advice, technically?)
Arguably higher fall damage from higher heights models acceleration. If there were no acceleration then fall damage would be the same regardless of the distance you fell.
But if we’re (incorrectly) interpreting the RAW as the laws of physics, then the fall damage isn’t modeling some underlying law of physics. It just is the law, there isn’t some underlying physical property called “acceleration” to talk about.
