Two identical cylindrical disks have a common axis. Initially one of the disks is spinning. When the two disks are brought into contact, they stick together. Which of the following is true?
A) The total kinetic energy and the total angular momentum are unchanged from their initial values.
B) Both the total kinetic energy and the total angular momentum are reduced to half of their original values.
C) The total angular momentum is unchanged, but the total kinetic energy is reduced to half its original value.
D) The total angular momentum is reduced to half its original value, but the total kinetic energy is unchanged.
E) The total angular momentum is unchanged, and the total kinetic energy is reduced to one-quarter of its original value.

Question

Quizplus · Accepted Answer

The total angular momentum is conserved because no external torques act on the system. However, the kinetic energy is reduced due to the inelastic nature of the collision, where the two disks stick together, resulting in energy loss. The final kinetic energy is one-quarter of the initial kinetic energy of the spinning disk.

Two Identical Cylindrical Disks Have a Common Axis