Physics H131: Hints for Problem Set #17

Chapter N12 Problems

• N12B.3: What does "geostationary" imply for the satellite's period? Which of Kepler's laws relates period and radius?
• N12B.4: There are different ways to solve this. One involves the moon's period which is 27.3 days. For the other you need to to know the earth's mass.
• N12B.7: Third law!
• N12S.5: What is the deeper principle behind Kepler's second law? Are the condition for the application of this principle satisfied?
• N12S.8: Review the proof we gave for Kepler's third law and modify it appropriately.
• N12S.11: (a) Under which condition is the distance D between he two stars a well-defined quantity? What additional assumption do you therefore have to make? (b) Use Eq. (N12.28) to re-calculate D and compare. How (in)accurate was your result in (a) (in percent of relative deviation)?
• N12R.1: This is another application of our famous formula for the orbital velocity in a circular orbit!

Chapter N13 Problems

• N13T.5: What if you added to the relationship a factor of mass m on each side?.
• N13B.4: Third law!
• N13S.4: (a) See N12B.4. (b) How do your energy and angular momentum change? Remember that energy and angular momntum determine all characteristics of the new orbit.
• N13S.9: At fixed angular momentum, how is the energy of the system related to the eccentricity of the orbit? What are the limits on eccentricity? What does this imply for the energy? Is the result compatible with your intuition?
• N13R.1: This very similar to the orbit problem discussed in Example N13.3 (page 235). In the new orbit, what should be the speed of the spaceship in its present position? How can you achieve this?