1. The problem statement, all variables and given/known data At the instant shown, the rod R is rotating about its centre of rotation with ω=3.8rad/s. mA=10kg; The pulley, with mP=8.7kg and RP=0.2m, may be modelled as a uniform disc. The rod, with mR=4.1kg and L=0.8m, may be modelled as a thin beam rotating about one end. g=9.8m/s ². What is the magnitude of the acceleration of point B at this instant? 2. Relevant equations ΣF=ma (N2) ΣM=Iα (Eulers equation) 3. The attempt at a solution IP=(1/2)MR2 IRod at centre of rotation=(1/3)ML2 I defined upwards and anticlockwise to be positive and thus derived the following equations: ΣFA=TA-mAg=mAaA ΣMP at centre=RpTA-RpTB=IPαP ΣMRod at end=-LTB+(1/2)LMRg=IRαR where TA= Tension force acting between A and pulley and TB=Tension force acting between rod and pulley I then found these constraints on aB in terms of aA,αP,αR -aB=aA 5aB=αP (-5/4)aB=αR assuming that aB is acting upwards Then, by subbing aB into the three original equations, I got the following system of equations: TA+mAaB=mAg RpTA-RpTB-5IPaB=0 -LTB+(5/4)IRaB=-(1/2)LMRg However, when I solve this system of linear equations I get the wrong answer. I have a feeling this is because I ignored the angular velocity of the rod but I can't see that would affect the acceleration of B.