1Q60.90 Marion’s Dumbbell

A simple apparatus to demonstrate the non-colinearity of the angular velocity vector and the angular momentum vector. Helps students increase their understanding of angular velocity, angular momentum, and the inertial tensor. Theory and construction details.

A long metal rod ends in hand grips. Part-way down the rod is a metal pulley set with its axis along the long axis of the rod. Beyond the pulley, the middle third of the rod is partially cut away, leaving about half the thickness. A smaller rod with a large sculpted mass on one side and a small sculpted mass on the other side is fastened to this flattened section of the large rod. The small rod is fastened at an angle and off-center, with the pivot point quite near to its larger-mass end. A set screw near the pivot anchors the off-center rod at a fixed angle. A string is currently wound around the pulley.

See AJP42(2), 100 for more information

Locations: Dumbbell C1-3