Which statement summarizes Kepler‘s first law of planetary motion A:planets in solar system revolve around the sun

B: planets revolve around the sun in elliptical orbits

C: planets closest to the sun move faster in their orbits than those father away

D: planets move fastest while earth is at perihelion

The man of mass m1 and the woman of mass m2 are standing on opposite ends of the platform of mass m0 which moves with negligible friction and is initially at rest with s = 0. the man and woman begin to approach each other. derive an expression for the displacement s of the platform when the two meet in terms of the displacement x1 of the man relative to the platform.