Kepler’s laws (and related stuff)

Only a link dump for now:

* “Newtonian Gravitation and the Laws of Kepler”:http://csep10.phys.utk.edu/astr161/lect/history/newtonkepler.html
* “Kepler’s laws proven”:http://dept.physics.upenn.edu/courses/gladney/phys150/lectures/lecture_nov_29_1999.html
* “Lecture slides on Gravity & planetary motion; Kepler’s laws; Energy and escape velocity”:http://www.phys.uconn.edu/~rcote/Courses/PHY151/lec28.pdf
* “Worked questions about satellites orbiting the Earth etc.”:http://www.br.psu.edu/faculty/lht1/concepts/harvard/lectures/lect15.html
* “Problem sheet soln on some gravitational stuff”:http://phy-lyman.princeton.edu/~page/phy105/03/ps7_soln.pdf