You gotta ask for help don't ya?

[MD Longhorn]

Originally Posted by Eastshire

Why would you draw a line, when the ball followed an arc? It's foul for me.

Vertically, yes, but it's vertical path is completely irrelevant. Over this very short distance the amount of arc on its horizontal path is exceedingly minimal (nevermind that the arc is in the opposite direction it would need to go to make the point you're trying to make relevant - don't believe me, spin a ball horizontally as much as you like, and observe the direction and magnitude of it's spin after a bounce --- oo, look --- not what you expected.)