Tough Gravity equations Two 1 kg objects are floating in free space 10 meters away from each other(and are not subjected to any other forces other than the gravitonal attraction they have for each other) How long will take for the two objects to come in contact with each other? This is tough because acceleration is constantly changing as they get closer together. I orginally tryed using the universal gravity equation to solve this, and ended up with the following 2nd order non-linear diff eq, which I cant solve x''=Gm(x^-2) ; want to solve for I was talking with my professor and he said there was an simplier way to solve this using Kelpers laws. I have no idea how to use kelpers laws to solve this problem sense the objects are rotating around eachother, rather they are moving in a straight line towards eachother. Can some one please point me in the right path to solving this problem using kelpers laws, or help me sovle the diff equation.