Chapter 21 Post-Lecture Quiz with answers

Chapter 21 Post-Lecture Quiz with answers - 1 Chapter 21...

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1 Chapter 21 Post-Lecture Quiz 1. What are possible reasons that galaxies differ in form? 1. Different density in the pre-galactic cloud 2. Different rotation of the pre-galactic cloud 3. Collisions between galaxies 4. 1 and 2 5. 1, 2, and 3 2. What is likely to happen if two galaxies collide? 1. Stars crash into each other 2. Gravitational pull greatly distorts each galaxy 3. Starbursts–greatly enhanced star formation–may occur 4. All of the above 5. 2 and 3 3. What is often found at the centers of clusters of galaxies? 1. Stars that have been pulled out of galaxies in collisions between galaxies 2. A very massive spiral galaxy 3. A very massive elliptical galaxy 4. None of the above 4. Why should we not be surprised that galaxy collisions were rather common in the past? 1. Galaxies moved faster in the past and therefore collided more often. 2. Galaxies were larger in the past and therefore collided more often. 3. Both (a) and (b). 4. The universe was much denser in the past, so its galaxies were much closer together, making collisions much more frequent. 5. Because elliptical galaxies are formed by the collision of two spiral galaxies, ellipticals are observed to be more common in the past. 5. Matter falling into supermassive black holes in the centers of galaxies is thought to be the source of: 1. Jets that shoot far into space 2. “Active” galactic nuclei 3. Strong radio emissions 4. Quasars 5. All of the above
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2 6. The black hole at the center of our own galaxy may once have powered an active galactic nucleus. 1. Yes, active nuclei in other galaxies appear to be powered by accretion into supermassive black holes. 2. Yes, the Milky Way has a very similar appearance to other galaxies with active nuclei. 3. No, the Milky Way is a spiral galaxy and only elliptical galaxies have active nuclei. 4.
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This note was uploaded on 03/03/2011 for the course RSM 100 taught by Professor Oesch during the Spring '08 term at University of Toronto- Toronto.

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Chapter 21 Post-Lecture Quiz with answers - 1 Chapter 21...

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