Hello, I have expression for the aceleration of a planet in the orbit of another planet and need to get the expression for it's velocity. The aceleration expression came from the Gravitacional Force within the gravitacional field of the planets. F=ma F=(-G.m1.m2/r^3) * position_vector Where r is the scalar value of the position_vector. From here we can get ax and ay. For the velocity: 1) Is it ok to do it Using a= Vf-Vi/tf-ti for each axis (ax ay).? 2) How would it be done using the intergration rules.? Thanks.