An 8-kg uniform disk of radius 200 mm is welded to a vertical shalt with a fixed end at B....

An 8-kg uniform disk of radius 200 mm is welded to a vertical shalt with a fixed end at B. The disk rotates through an angle of 3° when a static couple of magnitude 50 N • m is applied to it. If the disk is acted upon by a periodic torsional couple of magnitude T = Tm sin wft, where Tm = 60 N • m. determine the range of values of wf for which the amplitude of the vibration is less than the angle of rotation caused by a static couple of magnitude Tm.

Fig. P19.103