text: what is the speed of a satellite in orbit? the satellite has a mass of 150 kg, and it is launched into orbit at a height of 12,800 km above the earth's surface.  i got 4.558 x 10^14 m/s, but the answer is 4,558 m/s... did i do something wrong? the force acting on a mass of m kg  is   f = g m m / r^2  where  g =6.673x10^ (-11) nm^2/kg^2; m, the mass of earth =5.978x10^24kg and r, the distance of the mass from earth  =  ( 12800 +6400)x10^3m.  the acceleration on the mass is   f/m = g m / r^2  this acceleration is the centripetal acceleration for the object  = v v /r.  equating the two and canceling one r from both sides,  v v = gm / r.   ---- = (6.673x10^ (-11) x 5.978x10^24) / r  ---- = 3.99 x 10^ 14 / r  ---- = 3.99 x 10^14 / 19.2 ^ 6   v = 4558 m/s