So if you have two masses connected by a massless string in a multiple pulley system as shown below, the acceleration will be different right? I ask because when doing normal pulley problems where two masses are connected by a single thread, you assume the acceleration is equal, though the net force would not be, to solve the problems. But in this case, the acceleration would not be equal, right? I understand it if i look at the lengths, as if you pull the left string down one meter the right will be shortened by an equivalent amount so between the two sections of that string, on the right each will shorten by .5. So the second mass should shorten/rise at a rate 1/2 of the mass on the left (which is falling). But i feel im missing a crucil distinction here. Rather than recognizing the type of problem id like to understand what makes the cases unique in considering the accelerations. Any help?