Maxwell's Wheel, Revolving Pendulum

Maxwell's wheel consists of a disk mounted on a horizontal axle, suspended on two threads from above. When the disk is rotated, the threads wind themselves on the axle, somewhat similar to a yo-yo, and the disk rises. Once at the top the threads begin to unwind, and the disk falls. Students can measure the dimensions of the wheel plus axle and calculate the moment of inertia. They can also measure falling distances and falling times of the wheel, and determine the downward acceleration.