9-23-08

The class period started with a short review of Aristotle's ideas about violent and natural motions, and how objects of different elements try to return to their place of origin. (notes page 2-4) Thankfully a guy named Galileo challenged Aristotle's ideas, he noticed while dropping two objects over the side of a building that they were both hitting the ground at the same time. (notes page 6). Proving that object of a different mass will fall at the same rate. Taking a little trip to the back of the classroom a demonstration of Galileo's Inclined Plane Experiment was performed. (notes page 6) The test proved that if an object dropped from a certain height (ball rolling down the incline) it will continue to move until it reaches the same height. (ball rolling up the other incline.) This is only true when there is no friction involved. So of course the ball loss some of its energy to friction and was not able to reach the exact same height of which it was dropped. The question was then asked, what if the second incline was removed? The answer, with out friction the ball would continue to roll in a straight line and at a constant speed until it returned to the original height of which it was dropped.

Galileo's Inclined Plane Experiment- If a ball is dropped from 2 feet it will continue at the same speed and direction until it reaches its original starting point. The subject of Newton's first Law (notes page 8) was discussed and some fruit was sliced in the process. A simple experiment that you can perform in your kitchen at home (or any other room...I don't care) is to fill a glass with water and place it on top of a sheet of paper. Move the paper and the glass to the edge of the table. The weight of the glass will keep the paper from moving from underneath it. Once at the edge a quick jerk of the paper will allow it to overcome the inertia caused by the glass and the paper will be removed from the underneath the glass. A video was shown (click links below)

http://es.youtube.com/watch?v=BwkUNrSCNMg http://es.youtube.com/watch?v=Hyw9uNF4nmE&feature=related