Can anyone tell me how the red-marked result came? I did not understand this "dL" part. I know Pythagorean formula is used here but how the final result came?
What I was getting at is that there's no unit sensitive constants that are part of the formula. If I say v = 32.2*t it is implied that v is in feet/sec and t must be in seconds to make sense if it's acceleration due gravity near the Earth's surface.
If I say v = a*t, then there is no sensitivity; the units just need to be consistent. v furlongs/fortnight = a furlongs/fortnight^2 * t fortnight.
I guess that's one way to look at it - for me all such things are scaled. I recall the discussion that all parabolas are identical, but people look at different parts of them and think they are different.