The uniform semicircular bar of radius r = 145 mm and mass m = 3.0 kg rotates freely about a horizontal axis through the pivot O. The bar is initially held in position 1 against the action of the torsional spring and then suddenly released. Determine the spring stiffness KT which will give the bar a counterclockwise angular velocity w = 4.8 rad/s when it reaches position 2, at which the spring is undeformed. A KT Part 1 m 2 A' Measure gravitational potential energy from point O. Find the gravitational potential energy in positions 1 and 2.

The uniform semicircular bar of radius r = 145 mm and mass m = 3.0 kg rotates freely about a horizontal axis through the pivot O. The bar is initially held in position 1 against the action of the torsional spring and then suddenly released. Determine the spring stiffness KT which will give the bar a counterclockwise angular velocity w = 4.8 rad/s when it reaches position 2, at which the spring is undeformed. A KT Part 1 m 2 A' Measure gravitational potential energy from point O. Find the gravitational potential energy in positions 1 and 2.