So I understand the equation f=g*m1m2/d^2 and I understand how to use it, but I'm unsure what my results actually mean. Once I have calculated the force, I don't know what the strength implies. How much force do I need for one object to orbit another? How much is so much that the objects become 'attached' to one another (like we are to the earth)? How much is too little? Also, if we look at binary stars, they are both attracted to each other with a similar force due to their masses. What strength is required for this to happen? If I were to put two cars in space, they certainly wouldn't be massive enough to pull at each other. But how big/close together would two objects have to be in order for this to happen?