If we consider a simple case like the following we can write the acceleration of the block as $(m2-m1)g/(m1+m2)$ considering that $m2$ is heavier than $m1$
It is possible if the pulley is frictionless and massless and the string too is fricionles and massless and also inextensible
But what if
the string is not massless
string is not frictionless
string is frictioless but the pulley has mass
etc Etc...... please help me applying my concepts.
edit: another doubt too arised Is it true that wherever the rope touchs an object it applies a force same as its tension? If yes then how is the following valid:
If no then how is $N = 2T$?