Homeworks 1

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Homeworks 1
Homeworks 1
Example.jpg
About this Assignment
Topics
Chapters 1 - 3
Lectures 1 - 5

Homeworks 1 is the attempted solution to our second task[1] in the course Introduction to Astrophysics. This assignment is due on Wednesday 09/09/09 and was assigned on 09/01/09. Solutions were created by Group 1 (RyanT, KimW, SaraC, ZackM, TiaraD)

Problem 1

List in order of increasing size and give the approximate size of the following objects: An atom, a biological cell, a cluster of galaxies, the Earth, a galaxy, the Local Group of galaxies, a neutron, a neutron star, a person, the Solar System, our sun. Note: you may have to look in other books besides your textbook to get all this information.

There are 3 ways to approach this problem: By radius, by volume, and by mass

By Radius

  1. Neutron = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 3 quarks \;} (or Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle r \approx 1 fm \;} = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 1.11 \times 10^{-15} m \;} ) [2] [3] [4]
  2. Atom = empirical atomic radius Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle r \approx 62 - 520 pm \;} = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 62 - 520 \times 10^{-12} m \;} [5] [6]
  3. Biological Cell = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 10 \mu m \;} [7] [8]
  4. Person = 4'11" = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 1.4986 m \;} [9]
  5. Neutron Star = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 12 km \;} = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 1.2 \times 10^4 m \;} [10] [11]
  6. Earth = radius of the Earth = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 6378.1 km \;} = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 6.3781 \times 10^6 m \;} Cite error: Closing </ref> missing for <ref> tag
  7. Solar System = radius of the comet Oort Cloud's orbit = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 7.5 \times 10^{12} km \;} = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 7.5 \times 10^{15} m \;} [12]
  8. Galaxy = radius of most galaxies = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 50000 ly \;} = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 4.73 \times 10^{20} m \;} [13]
  9. Local Group of Galaxies = radius of Local Group = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 5 \times 10^6 ly \;} = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 4.73 \times 10^{22} m \;} [14]
  10. Cluster of Galaxies = approximate size of most clusters = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 5 Mpc \;} = Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 1.54 \times 10^{23} m} [15]

Problem 2

The nearest star outside the solar system is about 4 light years away.

  1. How far away is the star in kilometers?
  2. Suppose you travel to the nearest star in a rocket ship moving at 100 km per hour (100 km/hr is

about 62 mi/hr, a typical automobile speed on a Florida highway). How many years will it take you to get to the star?

  1. Suppose you travel to the star at 10 km per second (the speed of a rocket in orbit around the Earth). How many years will it take you to get to the star?

Problem 3

Use the size of the Astronomical Unit in kilometers and the length of the year in seconds to calculate how fast the Earth moves in its orbit in kilometers/second.

Problem 4

Describe the essential differences between the Ptolemaic, Copernican, and Keplerian descriptions of planetary motion.

Problem 5

Use Newton’s laws to show that the orbits of planets are ellipses.

Notes

  1. ↑ Our first task was to register our PRS, visit the course web-page on Blackboard, look at the textbook, and write an equation for our wiki
  2. ↑ Which is larger, the proton or the neutron? http://www.physlink.com/education/AskExperts/ae570.cfm
  3. ↑ What are the sizes of protons neutrons and electrons? http://wiki.answers.com/Q/What_are_the_sizes_of_protons_neutrons_and_electrons
  4. ↑ On the Radius of the Neutron, Proton, Electron and the Atomic Nucleus http://www.wbabin.net/physics/yue.pdf
  5. ↑ Information about Atomic Radii: http://www.webelements.com/
  6. ↑ J.C. Slater, J. Chem. Phys. 1964, 41, 3199.
  7. ↑ The Biological Cell on Wikipedia http://en.wikipedia.org/wiki/Cell_(biology)
  8. ↑ Campbell, Neil A.; Brad Williamson; Robin J. Heyden (2006). Biology: Exploring Life. Boston, Massachusetts: Pearson Prentice Hall. ISBN 0-13-250882-6
  9. ↑ Kim Wynne's height
  10. ↑ http://en.wikipedia.org/wiki/Neutron_star
  11. ↑ Paweł Haensel, A Y Potekhin, D G Yakovlev (2007). Neutron Stars. Springer. ISBN 0387335439.
  12. ↑ http://curious.astro.cornell.edu/question.php?number=374
  13. ↑ http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/001205a.html
  14. ↑ http://www.universetoday.com/guide-to-space/galaxies/local-group/
  15. ↑ http://www.damtp.cam.ac.uk/user/gr/public/gal_lss.html

References

  • B.W. Carroll & D. A. Ostlie (2007). An Introduction to Modern Astrophysics. Addison Wesley. ISBN 0-8053-0402-9
  • Lectures 1-4
  • Chapters 1-2
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