F = G M 1 M 2 d 2 , where F is the gravitational force between two point masses, M1 and M2; d is the distance between M1 and M2; G is the universal gravitational constant, usually taken as 6.670 × 1011 m3/(kg)(s2) or 6.670 × 10−8 in centimeter–gram–second units. a = F M 1 = G M 2 r 2 .
