Two solid spheres of equal size and mass are joined by a spring-loaded, extendible rod. The whole unit is spinning like a baton (end-over-end) 5 times per second. Suddenly the rod stretches, pushing the spheres farther apart. What change takes place as a result of the stretching?
A) The angular momentum of the spheres and rod decreases.
B) The angular momentum of the spheres and rod increases.
C) The rate of spin of the spheres and rod decreases.
D) The rate of spin of the spheres and rod increases.

Question

Quizplus · Accepted Answer

The angular momentum of the system (spheres and rod) is conserved. When the distance between the spheres increases due to the stretching of the rod, the moment of inertia of the system increases. To conserve angular momentum, the rate of spin (angular velocity) must decrease.

Two Solid Spheres of Equal Size and Mass Are Joined