Wa alaikum assalaam wa rahmatullahi wa barakatuh, 1. When the
last letter of a word has a shaddah on it, and we are stopping
on the word, the only way to form the letter is with collision
of the two participating parts of articulation. It is impossible
to have collision of the first part of the shaddah, and separate
before colliding again for the second part of the shaddah, for
if we do this, we will be putting a vowel on the first part of
the shaddah, which as we know is saakin. Physically we cannot
just by normal letter formation make clear that there are two
letters on shaddah when stopping on it (outside of the
exceptions we have stating in the lesson on the . The only way
to make clear that there are two letters (the two parts of the
shaddah) is by making a , or accent. This makes clear there are
two letters. There is no other way to do it without adding a
vowel or qalqalah to the first letter of the shaddah. We stated
in the lesson you are referring to: When stopping on a word like
this, we stop with on