The definition of velocity: r v ! r r d dt d r v dt. The kinematic equations: v = v: + at x = x, + v t + 1. 2 v 2 = v o x ! x o = 1. Ab cos" = axbx + ayby + azbz. Acceleration due to gravity g = 9. 80 m/s2. Earth - mass: 5. 98 x 1024 kg radius: 6. 38 x 106 m. Moon - mass: 7. 36 x 1022 kg radius: 1. 74 x 106 m. Sun - mass: 1. 99 x 1030 kg radius: 6. 96 x 108 m. Earth - moon distance: 3. 82 x 108 m.