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Astr 2010 Problems in Planetary Astronomy

Astr 2010 Problems in Planetary Astronomy. Thursday 11:10am – 12:05pm Sundquist Science Center B-107 Dr. Spencer Buckner www.apsu.edu/astronomy. Instructor Dr . Spencer Buckner. Office: SSC B – 326 Hours: MWF 10:15am – 12:15pm MWThF 2:30 – 4:30pm or by appointment

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Astr 2010 Problems in Planetary Astronomy

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  1. Astr 2010Problems in Planetary Astronomy • Thursday 11:10am – 12:05pm • Sundquist Science Center B-107 • Dr. Spencer Buckner • www.apsu.edu/astronomy

  2. InstructorDr. Spencer Buckner Office: SSC B – 326 Hours: MWF 10:15am – 12:15pm MWThF 2:30 – 4:30pm or by appointment Email: buckners@apsu.edu Phone: 221-6241

  3. 21st Century Astronomy: The Solar System, 3rd Edition,by Hester, Burstein, Blumenthal, Greeley, Smith & Voss Textbook If you don’t have the book, don’t go buy it since it isn’t required. Mostly we will just use the problems in the back of the chapters

  4. Grading Exams…………45% 90 – 100…A Homework…….30% 80 – 89…..B Projects………..20% 70 – 79…..C Participation…….5% 60 – 69…..D <60……….F

  5. There will be three one-hour exams during the semester. The exams will be entirely problems similar to the homework problems. A formula sheet will be given out with the exam. Tentative exam dates are • September 27 • November 1 • December 10 @ 10:30am • A scientific calculator will be required for the exams Exams

  6. Homework Homework will be assigned from the Student Questions at the back of each chapter in the 21st Century Astronomy textbook. Additional problems from other sources will also be assigned to supplement the back-of-chapter questions. They will be due at the beginning of the next class meeting. First Homework set is due next week. Chapter 1 # 24, 26, 27, 31, 34, 35 & 37 Solutions to the homework will be posted in the class D2L shell a day or two after they are turned in.

  7. Project There will be two projects assigned during the semester. The first project will be due October 18. The second project will be due at the final exam period: Monday December 10 @ 10:30am. In addition to a written report, you will make a short (10-15 minute) oral presentation on your project. Since there are only two of you, you will not work in a group.

  8. First Project What is the annual cost of the light in this picture?

  9. Example Problem Mars is currently 1.7924 AU from Earth and the speed of light is 299,792 kilometers per second. If you were trying to drive the Mars rover Opportunity, how long would it take for your driving command to reach the rover? Do you think you will be able to avoid the big rock in front of the rover or will you crash into it, destroying the multimillion dollar machine?

  10. How to work a problem • Step 1: What are you trying to solve for? • Step 2: What information are you given? • Step 3: What equation(s) do you need to solve the problem? • Step 4: Plug in the numbers and solve the problem • Step 5: Check for reasonableness

  11. Answer the first two questions • Step 1: What are you trying to solve for? Light travel time from Earth to Mars. • Step 2: What information are you given? Speed of light (299,792 kilometers/second) and distance from Earth to Mars ( 1.7924 AU)

  12. Step 3: what equation(s) do you need? Look for example problems in the chapter, in the appendix, in other textbooks or online. For this problem, look on the equations sheet. The average velocity is the distance divided by the time So the time is the distance divided by the velocity

  13. Unit Conversions Distance was given in AU and velocity was in kilometers per second. Consistent units are needed throughout. Convert distances to meters and velocities to meters per second A word about significant figures

  14. Step 4: Plug in numbers and solve d = 2.6813946x1011 m v = 2.99792x108m/s

  15. Step 5: check for reasonableness Is this reasonable? How do I know if is reasonable? Is the rover going to crash into that big rock?

  16. An Example for You The Voyager 1 spacecraft, launched on September 5, 1977, the most distant manmade object, is currently located 121.57AU from Earth. If the velocity since launch has been constant (it hasn’t but we will assume it has for this problem) determine how long it will take to reach Alpha Centauri, 4.36 lightyears away?

  17. Example for You Solution • What are you trying to find? Travel time to Alpha Centauri at Voyager 1’s average speed • What information is given?Current distance to Voyager 1 is 121.57 AUTime since Voyager 1 launch is 6 days less than 35 yearsDistance to Alpha Centauri is 4.36 ly • What equation is needed?

  18. First find speed of Voyager The unit conversions AU to meters and years to seconds can be done directly in the calculation. The answer will come out in meters per second. Since this is an intermediate step, carry as many digits as your calculator gives you

  19. Next find travel time to Alpha Centauri Again, unit conversion lightyears to meters can be done directly in the calculation. Convert this to years to check for “reasonableness” That’s a long time!!!

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