PHY 101 Lecture Notes - Lecture 2: Mechanical Equilibrium, Net Force
Document Summary
Aristotle on motion: aristotle divided motion into two main classes. Proceeds from the nature of an object, dependent on the combination of the four elements. Motion straight up or straight down from an object naturally falling (due to gravity) or rising (smoke) Motion that is caused by an external forces. When objects move not by their nature. Has difficulties because the pushes and pulls responsible for motion are not always evident: quintessence. Slight difference due to the different air resistances on the different objects. Ball rolling down a steeper hill picks up more speed. Ball rolling up a steeper hill decreases speed. No slope makes the speed of the ball remain constant. Friction is what slows the ball down to a stop. In the absence of friction, if the ball is rolling on a horizontal surface, it will continue moving at the constant speed forever, and not slow down.
