Can acceleration be heard? │ The History of Mathematics with Luc de Brabandère
How did Galileo disprove Aristotle’s theory that a body falls at a constant speed?
By listening to what he could not see.
Galileo placed bells along a slope so the could hear a rolling ball striking them on the way down, making the important discovery that the ball’s speed increased as it travelled further. #
Find out more:
Galileo’s top experiments - https://www.pbs.org/wgbh/nova/physics...
How did Galileo prove Aristotle wrong about the speed of a falling body? By rolling balls down a slope.
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Today, scientists have machines, lasers, videos, cameras etc. But it was not always the case.
Galileo for example, in the 17th century, had no instruments at all. Nevertheless, he made some breakthroughs in science. I'll give two examples. And the two examples are connected because twice he proved Aristotle wrong.
The first idea of Aristotle was a heavy body falls faster than a light body on the ground. Galileo said no, it's not true. The speed is the same. He said: ‘Imagine a heavy rock and a light rock stick together. What's the speed of the fall? On one hand the sum is heavier, it should fall faster. But on the other hand, because of the light rock it should slow the fall down a little bit.’ So, this is a paradox and the only way to get out of the paradox was to accept speeds are the same whether it's a heavy or light body falling to the ground.
Another mistake of Aristotle, according to Galileo, was his belief that the speed of a falling body was a constant. 1 second, 1 metre, 2 seconds, 2 etc. Galileo was convinced, no, no, this was not true. There must be, somewhere, an acceleration. And he wanted to prove it.
Of course, no camera, no laser, nothing to prove it with instruments. How did he do it? He built a slope, a long slope, 16 metres. And let a ball roll along this like this. And then he said, I'm going to put some bells there. His idea was I cannot solve, and I cannot prove the problem with my eyes. I will solve the problem with my ears. And along the slope, he put bells equal distance. He let the ball roll.
And what did he hear? ‘Ping, ping, ping, ping, ping’ - the acceleration. He heard the acceleration. Incredible. Like this, Aristotle was proved wrong after 2000 years.
And Galileo didn't stop there. He said okay now I've proven the acceleration, let's calculate it. So, he started to play with the bells and organise them and finally he put the bells at 1, 2, 4, 8, 16 metres. And when he let the ball roll, he heard: ‘Ping, ping, ping, ping,” a constant rhythm. It was proven, acceleration is connected to the square of the distance.
Amazing, bravo Galileo.
Join us next time when we will admire one of Isaac Newton's most beautiful mathematical solutions.
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