The mechanism is released from rest with θ = 180°, where the uncompressed spring of stif...

The mechanism is released from rest with θ = 180°, where the uncompressed spring of stiffness k = 900 N/m is just touching the underside of the 4-kg collar. Determine the angle θ corresponding to the maximum compression of the spring. Motion is in the vertical plane, and the mass of the links may be neglected.