1. The problem statement, all variables and given/known data Three bodies with masses m1 m2 and m3 connected with a string through a sheave with a body with mass m4. The system is moving right. Write the second Newton law for the movement of the objects. Ignore friction. 2. Relevant equations 2nd law for bodies: m4a= m4g-T(the force of stretching the string) m1a= T m2a= T m3a= T 3. The attempt at a solution By summing up the last three equation I got: a(m1+m2+m3)=3T but it is apparently incorrect. The book equation is: a(m1+m2+m3)=T, how? Where am I wrong at?