ASTR HW 8 (Lecture 10 and 11)

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Before starting these questions, please watch Lectures 10 and 11. You must submit them at one time. The submit button is at the bottom. Please only submit once.

Moment of inertia (please select all that apply) *

1 point

is a property of objects that depends on their masses and geometries.

is a property of objects that depends solely on their masses.

is a property of objects that depends solely on their geometries.

is a quantity that is always conserved.

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Our Sun's radius does not rapidly decrease or increase because *

1 point

the Sun's radiation pressure balances its gravity.

the Sun's radiation pressure balances its neutrino emissions.

the Sun's gravity balances its sunspots.

the Sun's radiation pressure compresses the Sun.

⏩ FORM_TIMER_UNIQUE_IDENTIFIER *

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A star that begins its life with 30 solar masses *

1 point

will live a short life (~millions of years), and mostly likely produce a black hole after it explodes.

will live a moderately long life (~a few billions of years), and mostly likely produce a black hole after it explodes.

will live a short life (~millions of years), and mostly likely produce a neutron star after it explodes.

will live a short life (~millions of years), and mostly likely produce a white dwarf.

A core-collapse supernova occurs because *

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the gravity of a red giant gets weaker until it suddenly disappears, causing the start to suddenly explode.

the radiation pressure of a red giant increases continuously until the star explodes.

iron cannot be fused into heavier elements in a normal stellar environment.

helium cannot be fused into heavier elements in a normal stellar environment.

The below picture depicts a cube that is free to rotate around the horizontal, red dashed line. It suddenly shrinks, but its mass stays the same. What happens to the speed of its rotation? *

1 point

it increases

it decreases

The rotation speed stays the same, but the gravity of the cube changes.

The rotation speed may increase or decrease, depending on whether or not the cube is hollow.

The below picture is of a spiral galaxy, and the bottom left bright spot is emanating from place near the edge of the galaxy. What might this bright spot be? (This image is of the visible part of the spectrum, also known as the optical.) *

1 point

a single supernova

a protoplanetary disk in the process of formation

a gamma ray burst which has just occurred, and has not had time to cool.

a brown dwarf that is exceptionally large.

The leading hypothesis for the formation of the Solar System explains the shape of the Solar System primarily via *

1 point

conservation of angular momentum

nuclear fusion

wave-particle duality

heleoseismology

The person below is a tightrope walker who is carrying a large stick. What is the purpose of the stick? *

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The stick has a relatively small moment of inertia, thus decreasing the tightrope walker's overal moment of inertia.

The stick has a large angular momentum.

The stick has a relatively large moment of inertia, thus incressing the tightrope walker's overal moment of inertia.

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