The torsional spring at A has a stiffness of k = 900 N•m/rad and is uncoiled when θ = 0°....

The torsional spring at A has a stiffness of k = 900 N•m/rad and is uncoiled when θ = 0°. Determine the angular velocity of the bars, AB and BC, when θ = 0°, if they are released from rest at the closed position, θ = 90º. The bars have a mass per unit length of 10 kg/m.