Gravity = the attractive between objects: weight = gravitational force exhibited on object by earth, mass = amount of material, newton"s law of gravity- describes pull two objects have on each other. F = g(mm/r^2: m = mass of pulling object m = mass of object being pulled r. = distance between objects: force of attraction is proportional to mass, relationships between force and distance = inverse square law, distance gets bigger ---> force gets smaller. If an object exerts force on you, you exert the same force back on it. A: for every action there"s an equal and opposite reaction, equation = conservation of momentum, m*v* = m^v, * and ^ denote mass and velocity of separate objects, mv = momentum. Orbit: orbit = constantly falling, leo = low earth orbit, leo ---> 5 mi/ second = 90 minutes to circle the earth.