The 12-lb lever OA with 10-in. radius of gyration about O is initially at rest in the ve...

The 12-lb lever OA with 10-in. radius of gyration about O is initially at rest in the vertical position(θ = 90°), where the attached spring of stiffness is unstretched. Calculate the constant moment M applied to the lever through its shaft at O which will give the lever an angular velocity as the lever reaches the horizontal position θ = 0.