The equation that governs the circular orbit of a satellite is t = 2(pi)√(r3 / gme) where me is the mass of the earth, which is approximately 6 x 1024kg. assuming a circular orbit, to achieve an orbit at 20,000km, what would the speed need to be?

Students in an introductory physics lab are performing an experiment with a parallel-plate capacitor made of two circular aluminum plates, each 11 cm in diameter, separated by 1.0 cm. how much charge can be added to each of the plates before a spark jumps between the two plates? for such flat electrodes, assume that value of 3×106n/c of the field causes a spark.