[" A spherical planet far out in space has a "],[" mass "M_(u)" and diameter "D_(u)" .A particle of "],[" mass "m" falling freely near the surface of "],[" this planet will experience an acceleration "],[" due to gravity which is equal to "],[[" (1) "(GM_(0))/(D_(0)^(2))," (4) "(GmM_(0))/(D_(0)^(2))]]