The Study of Motion: From Aristotle to Galileo - Prof. Brian N. Espino, Papers of Physics

Download The Study of Motion: From Aristotle to Galileo - Prof. Brian N. Espino and more Papers Physics in PDF only on Docsity! Chapter 3 How things move • Aristotle’s physics • some motions, occurred without assistance • these were called natural motions – rock falling to Earth – water flowing downhill – smoke rising These motions were in the vertical direction Galileo • Galileo studied falling motion. • His Law “If air resistance is negligible, any two dropped objects will hit the ground at the same time. • Also rolled objects up and down inclines. Law of Inertia • inertia – an object’s tendency to keep moving or stay at rest. • If a body is not subject to any external forces, an object at rest will stay at rest. If it was moving, it will continue to move in a straight line with a constant speed. Speed and Velocity • speed – the distance an object travels divided by the time taken to cover the distance • average speed – the average rate an object covers a distance average speed = distance traveled/traveling time s = d/t • instantaneous speed – the speed of a particle at a brief instant in time Free fall • Free fall is an example of 1-dimensional motion. • An object is experiencing free fall when the only influence is from gravity. • the acceleration of gravity is 9.8 m/s2 • For every second an object falls, its velocity increases in magnitude by about 10 m/s. (about 9.8 m/s) Free Falling Bodies For free falling objects the acceleration is due to gravity; a = g = 9.8 m/s2 in the downward direction. (if the coordinate system states that up is positive, the gravity is negative) For close estimates you can use g = 10 m/s2 Suppose you dropped a ball from a high cliff. After each second interval, the magnitude of the ball’s velocity increases by about 10 m/s. Notice that in each 1 second time interval, the distance traveled increases. Here is the equation for position versus time: x = v0*t + ½ a*t 2 The displacement as a function of time is quadratic. Time (s) Velocity (m/s) 0 1 2 3 4 0 10 20 30 40