The garage door CD has a mass of 50 kg and can be treated as a thin plate. Determine the...

The garage door CD has a mass of 50 kg and can be treated as a thin plate. Determine the required unstretched length of each of the two side springs when the door is in the open position, so that when the door falls freely from the open position it comes to rest when it reaches the fully closed position, i.e., when AC rotates 180°. Each of the two side springs has a stiffness of k = 350 N/m. Neglect the mass of the side bars AC.