F=G(Mm/r²), where G=gravitational constant(6.672...E10^-11 m^3 kg^-1 m^-2), M=Mass of earth, m=Mass of satellite, and r²=distance between earth and satellite squared. NOTE: this formula is used to figure the force of the satellite. Using Newton's second law, a=F/m, we can know it's acceleration, which can figure velocity change from the acceleration.