The variable-resistance motor is often used for appliances, pumps, and blowers. By applying a current through the stator S, an electromagnetic field is created that “pulls in” the nearest rotor poles. The result of this is to create a torque M about the bearing at A. If the rotor is made from iron and has a cylindrical core of mass M₁, diameter d and eight extended slender rods, each having a mass M₂ and length l, determine its angular velocity at time t starting from rest.

Given: M = 3 kg M1 1 = 100mm d = 50 mm M = 1 kg M2 M = 4 N-m t = 5 s