1. The problem statement, all variables and given/known data In a system where the atwood is suspended by a massless string with T3 and M1>m2. M1 is lower than m2. Relate Tensions and masses if it is frictionless, pulley and string are massless. 2. Relevant equations T1 is tension in string holding M1; T2 is tension in string holding M2. 3. The attempt at a solution I believe that when there is no acceleration: T3=M1+m2 T1=M1g T2=m2g but shouldn't T1=T2? when there is acceleration then the system CM does not change, but the CM of M1 and m2 is lowered since M1 falls lower. Or will it stay the same since M1 is already lower than m2? also, since T3 is being taken into account (which I cant find an example of), will it have a negative tension compared with the other tensions?