Rotational Inertia Set

With this set, students will learn that the speed of an object rolling down a ramp is determined by the shape or distribution of mass of an object

How It Works:

Two different shapes (for example, a ring and a disk) of the same radius rolling down an inclined ramp reach the bottom at different times because their rotational inertias are different. The straight side of the release mechanism holds the objects in place on the ramp and allows both objects to be released from rest at the same time in the same position. To release two objects of different radii (i.e., the small disk and the large disk), the stepped end of the release mechanism is used to hold the center of the objects at the same starting position.

Students learn that the speed of an object rolling down the ramp is not affected by its mass or radius. The shape or distribution of the mass determines the outcome. The sphere will reach the bottom first, followed by the disk. The ring will be last.

An interesting addition is to compare a Dynamics Cart with the sphere. The Dynamics Cart will win the race with the sphere because very little of the cart's mass is rotating.