Demos: 1Q-13 Hinged Stick and Falling Ball
This demonstration illustrates the difference between angular and linear acceleration. Start the demonstration by preparing the device as shown in the picture. With a quick swift motion, remove the stick between the two boards in such a way that neither board is disturbed in a horizontal direction. If done properly the ball will land in the cup. The physics behind the demonstration is this. Every point on the falling board has the same angular velocity (it is rotating about a hinge which connects the two boards) and the same angular acceleration. However, not every point on the board will have the same linear velocity and linear acceleration (linear velocity and acceleration is dependent upon the distance from the axis of rotation). Since the ball and cup are at two different locations they will have the same angular acceleration. However the ball will land in the cup when the board collapses because they will have different linear accelerations. There are two balls with different masses that come with this demonstration so you can show that mass does not affect the outcome of this demonstration.