Question1

A professor's office door is 0.92 {rm m} wide, 2.0 {rm m} high, 4.0 {rm cm} broad; has a mass of 25 {rm kg}, and pivots on frictionless hinges. A "door closer" is attached to door and the top of the door frame. As door is open and at rest, the door closer exerts a torque of 4.9 {rm N}cdot {rm m}.

A: What is moment of inertia of the door?

B: If you let go of the open door, what is its angular acceleration immediately afterward?

Question2

The picture tube in an old black-and-white television uses magnetic deflection coils rather than electric deflection plates. Assume an electron beam is accelerated through a 50.0-kV potential difference and then throughout a region of uniform magnetic field 1.00 cm wide. The screen is located 10.0 cm from the center of the coils and is 50.0 cm wide. When field is turned off, the electron beam hits the center of the screen. Ignoring relativistic corrections, what field magnitude is essential to deflect the beam to the side of the screen?