Chair Wheel Swivel

Chair Wheel Swivel
Angular Momentum Question:?

In a lecture demonstration, a student sits in a motionless swivel chair holding a spinning bicycle wheel. The student then flips the wheel. When this is done, the student and chair begin to rotate also. Which of the following is an accurate statement concerning this process?

a.The chair will be rotating much faster than the the wheel, in the opposite direction.
b.The chair will rotate slower than the wheel, in the same direction.
c.Angular velocity and rotational kinetic energy are conserved in this process.
d.Angular momentum, but not rotational kinetic energy, is conserved in this process.

Is this C? I’ve seen this done, but I’m not exactly sure what’s happening.

In general, when friction is not considered, momentum is conserved — whether it is linear momentum or angular momentum. But since the angular momentum is now shared among the wheel, the student and the chair, the speeds are going to change. The kinetic energy changes because the student did some work when he or she flipped the wheel.

Chair transfer using the swivel to pivot the patient