Two identical solid disks A and B rest on a frictionless horizontal surface with…
PHYSICS · Single correct · AP · Physics 1: Algebra-based · Energy and Momentum of Rotating Systems · Energy and Momentum of Rotating Systems
Problem
Two identical solid disks A and B rest on a frictionless horizontal surface with their flat faces touching so that their rims are in contact. Disk A is initially spinning counterclockwise about its center; disk B is at rest. During the brief interval while the rims are in contact, there is no external torque on the two-disk system. Which statement best describes how the angular momenta of the disks change during this interaction?
(a) Disk A loses angular momentum, and disk B gains a smaller amount in the counterclockwise direction, with the rest converted to thermal energy.
(b) Disk A gains additional counterclockwise angular momentum, and disk B gains an equal amount of clockwise angular momentum.
(c) Disk A loses angular momentum, and disk B gains an equal amount in the counterclockwise direction.
(d) Disk A loses angular momentum, and disk B gains an equal amount in the clockwise direction.