This is designed to provide a simple, clean means of studying rotational dynamics. A 40 cm diameter disc is machined of aluminum plate, with provision made to locate three masses at any of seven radii on its upper surface.

Rotational torque is provided by a mass attached to a light cord passing over a pulley and wrapped around the hub. Since its mass is only 50 grams, disc acceleration is very slow-almost 15 seconds being required for the mass to fall a meter. This permits good, accurate, reproducible data, using only a meter stick, a stop watch, and balance. Of course a "Smart Pulley" can be used to send data to a computer for analysis.

Operation is beautifully smooth. Weight of apparatus is 7 kg.

 This table gives a hands-on look at the problems of torque and center of gravity. Its simplicity focuses attention on the actual forces involved, giving a clear, uncluttered picture of exactly what is happening. Students have said they like working with it because "it resembles a wheel balancer".

The disc, made of 4.8 mm aluminum plate, is balanced on a ground tool steel point, being free to rotate or to tilt in any direction. Diameter is 60 cm. Think of it, that is very big. To provide reference points and a means of hanging weights, 360 holes are drilled through it on 2 1/2 cm centers. X and Y axes are identified by broken recessed lines.

The circular level is set in the top of a hub. Both the hub and the center support post are stainless. All parts are inter-changeable for storage and lab set-up. Shipped with 5 Angle Hangers.

Shipping weight is approximately 11 kg.