Challenger Center: Garriott Science Challenge

Rotational Inertia

The moment of inertia of an object is a property that describes how difficult it is to rotate the object about an axis. Rotational inertia accounts for the stability of gyroscopes and bike-riders, and has applications for navigation of planes and figure skaters performing lightning-fast spins. A solid object has several axes about which it will rotate smoothly. Each of these axes are known as a Principal Rotation Axis. The moment of inertia of a rotating object is at a minimum when rotating about a principal rotation axis. If an object is not rotating about a principal rotation axis, it will tumble in a random manner. A good example is an unbalanced car tire that wobbles.

Richard Garriott will experiment with spinning a deck of playing cards. He will try to demonstrate both stable rotation and tumbling rotation. He will videotape the sports moves so that accurate, details views of the motion of the deck of cards can be studied.

Essential Questions

Is there a preferred axis along which a solid object will rotate smoothly?
What causes a solid object to tumble while rotating?
Can a tumbling solid object be made to rotate smoothly?

Is there a preferred axis for smooth rotation of a deck of cards in space? Can a deck of cards spin without tumbling in space? If so, how many different ways can you smoothly spin a deck of cards in space?

Click here to submit your prediction!

Classroom Activities

Elementary

Lesson: Rotational Inertia

Middle/High School

Student Resources