This is the demo problem that we’ll be discussing on Tuesday. I encourage you to give it a shot before coming to recitation.
Question: A uniform trap door to a cellar lies horizontal on a floor. The trap door has a mass of 7 kg and a length of 90 cm measured from the hinge. There is a solid spherical 5 kg knob of radius 4 cm attached to the trap door 80 cm from the hinge. Someone tries to open the trap door by lifting at an angle of 15 degrees from vertical with a force of 110 N. What is the angular acceleration of the trap door?