Archive for Meaning of Life

Alternative Galaxy Dynamics Examination

Posted in Education, The Universe and Stuff with tags , , , , on June 12, 2010 by telescoper

Time Allowed: ~1/H0

Study the following video and answer the questions below it. Or else.

1. Use the information provided about the Earth’s orbital speed to estimate the mass of the Sun. (Assume a circular orbit; 1 AU is 1.5 × 1011 m.)

2. Use the information provided about the Sun’s motion around the Galactic Centre to estimate the total mass interior to the Sun’s orbit. (Assume a circular orbit and that the mass distribution is spherically symmetric; you may quote Newton’s shell theorem without proof.)

3. Use the answer to Q2, and other information provided in the video, to estimate the mean matter density in the Milky Way.

4. Use the information provided about the size, shape and stellar content of the Milky Way to estimate the mean number-density of stars interior to the Sun’s orbit.

5. Use the answers to Q3 & Q4 to estimate the mean mass-to-light ratio of the Galaxy.

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