A uniform rod of length ‘l ’ is pivoted at one of its ends on a vertical shaft of negligible radius. When the shaft rotates at angular speed  ω the rod makes an angle  θ with it (see figure). To find θ  equate the rate of change of angular momentum (direction going into the paper)  ml212ω2sinθcosθ about the centre of mass (CM) to the torque provided by the horizontal and vertical forces FH and FV about the CM. The value of  θ is then such that :