Geography Essay example

8108 Words Jan 22nd, 2015 33 Pages
Chapter 2

Galileo’s Great Discovery: How Things Fall

Galileo Galilei (1564–1642), the famous Italian mathematician at the leading edge of the scientific revolution that was to sweep Europe, was curious about motion. He was an experimentalist who for the first time had the insight and talent to link theory with experiment. He rolled balls down an inclined plane in order to see how things fell toward the Earth. He discovered in this way that objects of any weight fell toward the Earth at the same rate – that they had a uniform acceleration. He surmised that if they fell in a vacuum, where there was no air resistance to slow some objects more than others, even a feather and a cannon ball would descend at the same rate and reach the ground
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Since forces in different directions act independently,
D.W. MacDougal, Newton’s Gravity: An Introductory Guide to the Mechanics of the Universe, Undergraduate Lecture Notes in Physics, DOI 10.1007/978-1-4614-5444-1_2, # Springer Science+Business Media New York 2012 17


2 Galileo’s Great Discovery: How Things Fall

he could time the descent of the ball and learn how forces act on the ball as if it were only moving in the down direction. From that he could deduce how a freely falling object would move. Why did he use a ramp to measure fall? It is because with the limited technical means then available to Galileo, he could not possibly have timed, with any reasonable accuracy, the rapid descent of a vertically dropped ball. Using an inclined plane allowed him to dilute the force of gravity and slow the ball down so he could time it with a water clock, where he could then compare the weight of water that poured out before and after each event. This told him the time intervals elapsed during the ball’s fall down the ramp, which were not necessarily the equivalent of the seconds of a modern clock.1 Galileo repeated this experiment many times to help remove some of the subjectivity in his measurements and thereby gain greater accuracy of the result. Galileo’s idea of using an inclined plane to accurately measure free fall as noted took advantage of his insight that forces act independently in each dimension. As we saw in Chap. 1, the downward, vertical

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