particle2 # circ.p2 # small particle in nearly circular orbit around a more massive one G 1 # gravitational constant m 1000 p .5 .5 0 0 # initial pos. & vel. of particle 0 m 10 p .7 .5 0 31.6228 # initial pos. & vel. of particle 1 # if potential is proportional to log(r), # m is mass of central particle, # central particle is still, # ratio of masses is very high, # and tangential speed of outer particle is sqrt(Gm) # then a circular orbit results. # in this example, sqrt(Gm) = sqrt(1*1000) = 31.6228