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Unformatted text preview: ASTRONOMY 294Z: The History of the Universe Professor Barbara Ryden PRACTICE MINI-EXAM Short Answer Problems 1) Who lived first: Kepler or Copernicus? Copernicus. (Kepler modified the Copernican model by adding elliptical orbits.) 2) If the density of the universe were greater than the critical density, would the universe be positively curved, negatively curved, or flat? Positively curved. 3) Which is more massive, an electron or a neutrino? An electron. 4) A newly formed zircon crystal contains 1000 uranium-238 atoms. How many uranium-238 atoms will be left after two half-lives? 250. 5) A galaxy has a radial velocity of 14,000 kilometers per second. Using Hubble’s Law, what is its distance from us? d = v/H = 14 , 000 km / sec / 70 km / sec / Mpc = 200 Mpc 6) Arrange the following objects in order of increasing mass: Jupiter, Sun, brown dwarf, Earth. Earth, Jupiter, brown dwarf, Sun. 7) Which has the longer wavelength, visible light or X-rays?...
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- Winter '08
- Astronomy, Proxima Centauri, radial velocity method