As an interstellar cloud of hydrogen gas shrinks in size, its rate of rotation
A)increases, because the force of gravity strengthens as the cloud shrinks.
B)decreases, because its angular momentum is conserved.
C)increases, because its angular momentum is conserved.
D)decreases, because the force of gravity strengthens as the cloud shrinks.
E)increases, because its total energy is conserved.

Question

Quizplus · Accepted Answer

As an interstellar cloud of hydrogen gas shrinks in size, its angular momentum is conserved. According to the conservation of angular momentum, if the radius of the cloud decreases, its rate of rotation must increase to conserve angular momentum. This is analogous to a figure skater spinning faster when they pull their arms in.

As an Interstellar Cloud of Hydrogen Gas Shrinks in Size