A stone is suspended from the free end of a wire that is wrapped around the outer rim of a pulley,. The pulley is a uniform disk with mass 11.0kg and radius 51.0cm and turns on frictionless bearings. You measure that the stone travels a distance 12.3m during a time interval of 3.10s starting from rest.
This is a torque problem. Fr = Ia = kmr^2 a = Mgr find M = kmr^2 a/gr = kmA/g = ? where A = 2S/T^2 and S = 12.3 m and T = 3.1 s. k = 1/2 for a solid disk.
So we have M = km 2S/gT^2 = (1/2)*11*2*12.3/(9.8*3.1^2) = 1.436641254 = 1.44 kg. ANS.