A professor's office door is 0.95 wide, 2.2 high, 4.0 thick; has a mass of 22 , and pivots on frictionless hinges.

A professor's office door is 0.95 wide, 2.2 high, 4.0 thick; has a mass of 22 , 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 5.8 .