1. The problem statement, all variables and given/known data The thin uniform rod in Figure 10-59 has length 4.0 m and can pivot about a horizontal, frictionless pin through one end. It is released from rest at angle θ = 40° above the horizontal. Use the principle of conservation of energy to determine the angular speed of the rod as it passes through the horizontal position. 2. Relevant equations 3. The attempt at a solution I don't really know.