Care to give us some answers
First paragraph is my understanding about why when looking from the train, the arrow seems to go normally, while when looking from the ground, the arrow falls like dropping a rock.
Second paragraph is a about the "capacitor paradox"
https://en.wikipedia.org/wiki/Two_capacitor_paradoxhttp://kirkmcd.princeton.edu/examples/twocaps.pdfThird paragraph is something that I've accidentally "discovered" by myself while trying to come up with a more intuitive explanation for the capacitor paradox. I still don't understand why the capacitor paradox doesn't happen any more when charging from a constant current source instead of a constant voltage source.
While in the 2nd paragraph the question was rhetorical, like in the "where banana" meme, in the 3rd paragraph my question is genuine. I don't understand why the difference when replacing a voltage source with a current source. It was yet another example of a "What is going on here?", as the OP asked, except this time the "What is going on here?" was about electricity, not mechanic.
As for why jumping from an apparent physics paradox about mechanic to another about electricity, it was because of the OP question "What is going on here?". The question is not about a formula, is about understanding.
Now, what does it means to "understand" something? That's a tough question. Usually it means to be able to deconstruct something into components one is familiar with. There is a saying the we can never "learn something", we can only "get used with something". The last one is a hint about how a mind works:
- there is an outside reality, that is there independent of us
- there is an inner reality, which is a draft representation of the outside reality
- the outside world is too complex to fit all in one's mind, so we decompose the world into simpler parts, and remember only those main ideas instead of all the details.
Well, how you decompose something? Imagine you have a continuous datastream coming from your sensory inputs, say you are a newborn hearing others talking for the first time. You don't know any words yet, the sounds are no different then a noise or a music, the audio datastream from your newborn ears has no meaning. So what does the brain do? It classifies.
The most frequent sounds are grouped by their similarities, and by their proximity to each other. At first, the grouping is fuzzy, but the more often a sequence of sounds occurs, like for example a word, the more that neural path is reinforced, and eventually the brain will auto-learn words. Won't know yet what the meaning of those words, but will know the sounds.
But hey, a neuron doesn't know that datastream is coming from a sound, an image, or maybe just from another inner thought. So it continues to fire and thus to reinforce certain neuro-paths and thus making new categories, this time between the words and the images, and so on.
Eventually, we get an inner representation of the most frequent "categories" out there. Those categories are the foundation. We feel we "understand" something when we manage to decompose that something into categories we already formed.
Why the long rambling about understanding, and about how a mind learn to make sense of a stream of sensory inputs and turns it into meaning? Because the "categories" by which a mind understands, the basic bricks are different from one person to another. A physicist will try to decompose by using categories like the laws or physics, a programmer will tend to see the world through the perspective of a different set of "categories" like algorithms or data, a mathematician will see the world as math, and so on.
"When all you have is a hammer, everything looks like a nail". All a mind has is its inner categories.
These basic "groups", in terms of which a brain makes an inner representation of the outside world, are keep morphing over our entire life. New categories may form (simply by repeated exposure), they can merge and consolidate, or they can refine by splitting into smaller groups, and so on.
That is why the inner representation of a same "something" will always be more or less different from one person to another. Each brain has its own neuro-pathways for a same datastream, its own "categories".
Another interesting aspect of a mind is about awareness, but this is already too long.
Why the wall of text, you may think. Sorry man, you asked for it.

And, to be honest, because I like rambling about things like these.
Helps me sorting out my own thoughts, so thanks for the question.