Physics 30 - April 27

Today we started looking at planetary motion and Newton's Law of Universal Gravitation.  This law states that there is a force that exists between any two objects that have mass.  This force is proportional to their mass and inversely proportional to the square of the distance between the masses.  We did examples 24 and 25 which used this law.  We then looked at how gravity causes uniform circular motion, particularly with objects in orbit around planets and stars.  This is called gravitational motion.  It is born from the fact that the centripetal force that causes the motion is supplied by gravity.  We derived some interesting relationships with this fact. We didn't quite get to assignment 3.8 but will tomorrow after we look at a couple of examples.