1. The 10-lb bar is pinned at its center O and connected to a torsional spring. The spring has a stiffness k = 5 lb # ft>rad, so that the torque developed is M = (5u) lb # ft, where u is in radians. If the bar is released from rest when it is vertical at u = 90°, determine its angular velocity at the instant u = 0°.
2. The 10-lb bar is pinned at its center O and connected to a torsional spring. The spring has a stiffness k = 5 lb # ft>rad, so that the torque developed is M = (5u) lb # ft, where u is in radians. If the bar is released from rest when it is vertical at u = 90°, determine its angular velocity at the instant u = 45°.