Why Is It Surprising to Find Spiral Arms in Spiral

question 81

Multiple Choice

Why is it surprising to find spiral arms in spiral galaxies?

• A) Spiral arms require new stars, and previous new stars should have already used up the interstellar medium; no new stars should be forming now.
• B) The variations in speed of the stars across galaxies are not high enough to twist the shape of the arms into a spiral.
• C) There is no known mechanism to generate spiral arms.
• D) The motions of the stars and differential rotation of the galaxy should have wound their arms tightly and made them blend and disappear.

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Definitions:

Marginal Revenue

The additional income received from selling one more unit of a product or service.

Demand Function

A mathematical representation showing the relationship between the quantity of a good that consumers are willing to buy and its price, along with other factors like income and prices of related goods.

Price Elasticity

The measure of how much the quantity demanded of a good responds to a change in the price of that good.

Marginal Cost

The additional charge associated with manufacturing an extra unit of a product or service.