A professor's office door is 0.96 m wide, 2.2 m high, 4.1cm thick; has a mass of 20 kg, and pivots on frictionless hinges. A "door closer" is attached to door and the top of the door frame. When the door is open and at rest, the door closer exerts a torque of 5.7 N*m. What is moment of inertia of the door in (kg*m^2)? and If you let go of the door what is its angular acceleration immediately afterwards in rad/s^2?