# Free Fall Problem Solving

It looks like they hit the ground at exactly the same moment.If one stretch of a river flows more rapidly than another, it may be only because the channel is narrower there, which is just an accident of the local geography.But there is something impressively consistent, universal, and inexorable about the way things fall.A contradiction in Aristotle's reasoning Galileo's inclined-plane experiment disproved the long-accepted claim by Aristotle that a falling object had a definite “natural falling speed” proportional to its weight.Galileo had found that the speed just kept on increasing, and weight was irrelevant as long as air friction was negligible.Anyone can speculate, but Galileo went beyond speculation and came up with two clever experiments to probe the issue.First, he experimented with objects falling in water, which probed the same issues but made the motion slow enough that he could take time measurements with a primitive pendulum clock.How the speed of a falling object increases with time Galileo's second stroke of genius was to find a way to make quantitative measurements of how the speed of a falling object increased as it went along.Again it was problematic to make sufficiently accurate time measurements with primitive clocks, and again he found a tricky way to slow things down while preserving the essential physical phenomena: he let a ball roll down a slope instead of dropping it vertically.It is inconceivable that Galileo was the first person to observe a discrepancy with Aristotle's predictions.Galileo was the one who changed the course of history because he was able to assemble the observations into a coherent pattern, and also because he carried out systematic quantitative (numerical) measurements rather than just describing things qualitatively.