Approximations.... and forces Hey. Just out of curiosity, why is it super important to round everything in physics, even stuff such as 2.666(place recurring sign above 6) rather than being able to use recurring signs and such? Wouldn't it be better to use recurring signs and radical notation and such? (My teacher usually tells us off if we do so... but aren't they better for purely precise answers?) Also, is it common in physics, and perhaps general mathematics, to use taylor series approximations and such for tedious-to-evaluate functions involving differentials and integrals? Two perhaps unrelated questions, but another out-of-the-blue question: Suppose I'm in this magical realm and on a frictionless surface. Let's say there's a rock... I don't know, 2 meters away from me? And I am "infinity" away from any other objects, borders or anything. (i.e. they are so far away, I'm going to consider their gravitational forces negligible) Now, according to Newton's law of Universal Gravitation, the rock is going to be exerting a gravitational force on me, and I will be exerting a force on it..... So we'll be moving towards each other until we collide (Please correct me if I'm pulling this all out of my "poop chute") and then I'd be moving in the direction the rock is moving (assuming it's more massive than I am) because of my lack of inertia, correct? If I wanted to calculate the distance the rock travels in, oh, say 5 seconds, I'd first have to use conservation of momentum for JUST before it hit and just after the collision and F = ma to find the acceleration of the two "stuck-together" masses, and then use the common physics formulas, right? Or did my understanding totally go down the drain at some point or another? I hope someone can help clarify my understanding of all of these interrelated subjects. Thanks alot for any responses.