Physics 110: Homework Questions

(Handout #5)

Homework #9 Due 8 Apr Deadline 12 Apr

9.1

Use Figure 23-19 to find the orbital velocity of matter in the galaxy NGC 3200 at distances of 10, 20, 30, and 40 kpc from the center. Use Equation 22-2 to find the amount of matter within each of these distances.

9.2

What evidence do we have that there is a massive black hole in the center of the Andromeda Galaxy?

9.3

Why is it so difficult for astronomers to measure the distances to far-away objects in the Universe? It is often found that astronomical objects evolve, or change, with time. If a tertiary distance indicator were discovered to undergo significant evolution, would that have any influence on its value in determining astronomical distances and, if so, what would the effect be?

9.4

How is Hubble's Law used by astronomers to measure distances to galaxies? Describe how Hubble's Law is explained as a consequence of the expansion of the Universe.

9.5

How do we know that quasars are very distant? How do we know that they are compact (that is, small in size)?

Homework #10 Due 15 Apr Deadline 19 Apr

10.1

Discuss the importance of viewing geometry on the observed features of active galactic nuclei.

10.2

How have the quasars evolved over the past 10 billion years? What evidence do we have that there may be dead quasars in the centers of normal galaxies today?

10.3

Compare the Virgo and Coma clusters with respect to distance, richness, and the types of galaxies found in their central regions.

10.4

Briefly describe the three different ways of measuring the total masses of galaxy clusters. Do the results from the different methods agree?

10.5

The hierarchical clustering model is currently believed to be the best explanation for the origin of clusters of galaxies. What are the features of this model? Why do astronomers say that galaxy clusters are forming at the present time?

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