Of course! I forgot when adding the vectors $S$ and $l$, $J$ kan take values of $|l-S| \leq J \leq J+S$. Thanks!

Cool. So that would mean that an object which moves with $v=0.9999c$ isn't appearing to be moving slow because then $v\neq0.9999c$ right? How can it be that an accelerating object approaching the speed if light ex. near a black hole, that it appears to freeze then and then isn't approaching the speed of light?

Thank you very much! All the answers are very well explaned!

I know but i'm talking about an "observed" velocity, which seems slower.

Okay read me answer which is just a reformulation.

i didn't notice that i missed the space . Thank you