As a rotating gas cloud contracts, it spins:
A)faster due to an increase in angular momentum.
B)slower due to a decrease in angular momentum.
C)at a constant rate.
D)faster due to conservation of angular momentum.
E)slower due to conservation of angular momentum.

Question

Quizplus · Accepted Answer

As the gas cloud contracts, its size decreases and its rotation rate increases due to the conservation of angular momentum. This means that the product of the cloud's mass, radius, and angular velocity remains constant. Therefore, as the radius decreases, the cloud must spin faster to maintain the same angular momentum. As the gas cloud contracts, it conserves its total angular momentum, which is the product of its mass, velocity, and distance from the rotation axis. As the cloud's mass moves closer to the axis, its velocity increases, which leads to a decrease in its distance from the axis. However, because the total angular momentum is conserved, the cloud must spin faster to maintain its original value. Therefore, the correct choice is D, faster due to conservation of angular momentum.

As a Rotating Gas Cloud Contracts, It Spins