Question

A solid wood door of width L and height h is hinged along one side. The thickness of the door is w. The door has a mass M. You stand in front of the door while the door is open and free to rotate about its hinge, and throw a piece of sticky mud of mass m at the door. The mud, which is travelling horizontally with speed v, hits the door right at the middle, and the door begins to swing. Find the angular speed of the door. The moment of inertia of the door for rotation about its hinges is (1/3)ML^2 . Hint: the picture works best from a top view, i.e. imagine a camera above the door. What would that camera see?

Answer 1