A certain satellite travels in an approximately circular orbit of radius 4.8 X 106 m with a period of 7 h 23 min. Calculate the mass of its planet from this information. Number \".7 I Units kg V eTextbook and Media Assistance Used m Assistance Used What is the centripetal force that provides the uniform circular motion? How is that force related to the centripetal acceleration? How is the acceleration related the speed? How is speed related to the distance around a full circle and the time taken to travel that distance? Key Ideas . The motion of satellites, both natural and artificial, is governed by Kepler's laws: 1. The law of orbits. All planets move in elliptical orbits with the Sun at one focus. 2. The law of areas. A line joining any planet to the Sun sweeps out equal areas in equal time intervals. (This statement is equivalent to conservation of angular momentum.) 3. The law of periods. The square of the period T of any planet is proportional to the cube of the semimajor axis a of its orbit. For circular orbits with radius r, T 2 4TT2 GM (law of periods), where M is the mass of the attracting body-the Sun in the case of the Solar System. For elliptical planetary orbits, the semimajor axis a is substituted for r