434 Chapter 6 Plane Kinetics of Rigid Bodies PROBLEMS Introductory Problems 6/33 The uniform 20-kg slender bar is pivoted at O and swings freely in the vertical plane. If the bar is re- leased from rest in the horizontal position, calculate the initial value of the force R exerted by the bearing on the bar an instant after release. 1.6 m Problem 6/33 6/34 The 20-kg uniform steel plate is freely hinged about the z-axis as shown. Calculate the force supported by each of the bearings at A and B an instant after the plate is released from rest in the horizontal y-z plane. 6/30 80 mm 250 mm 80 mm B