Galileo’s Leaning Tower of Pisa Thought Experiment: Acceleration due to gravity is independent of Mass. The Power of Thought Experiments.
Aristotle‘s theory of gravity earlier stated that objects fall at speed proportional to their mass, which means the heavier the object is, the faster it will fall under gravity. Heavier object accelerates greater under gravity was believed to be true in Aristotle’s Time till Galileo conducted a thought experiment that disproved Aristotle’s assertion.
According to a biography by Galileo’s pupil Vincenzo Viviani, in 1589 the Italian scientist Galileo had dropped two balls of different masses from the Leaning Tower of Pisa to demonstrate that their time of descent was independent of their mass. Via this method, he supposedly discovered that the objects fell at the same acceleration independent of their masses. This was contrary to what Aristotle had taught: that heavy objects fall faster than lighter ones, in direct proportion to weight. While this story has been retold in popular accounts, there is no account by Galileo himself of such an experiment, and it is accepted by most historians that it was a thought experiment which did not actually take place.
Whether the experiment is conducted in real or not, the thought experiment actually proves that objects would fall with the same acceleration under gravity, independent of their masses.
Galileo arrived at his hypothesis by a famous thought experiment outlined in his book “On Motion”.
Following is the amazing thought experiment.
Let's assume that Heavier objects do Fall Faster than the Lighter ones.
Now, Imagine two objects, one light and one heavier than the other one, are connected to each other by a string. Drop this system of objects from the top of a tower. If we assume heavier objects do indeed fall faster than lighter ones (and conversely, lighter objects fall slower), the string will soon pull taut as the lighter object retards the fall of the heavier object, and thus the net acceleration of the system (lighter and heavier object together) will be less than the acceleration of heavier object alone! Which is actually a contradiction of the original assumption. The system (lighter and heavier object together) is heavier than the heavy body alone and thus should fall faster than the heavy body, but it is accelerating slower than a heavy body, which is a contradiction of the terms.
In this way, the assumption is proved to be false.
If we assume otherwise that lighter objects fall faster than the heavier objects then also we will reach the same contradiction by a similar argument.
It leaves us with only one possibility that objects fall with the same acceleration independent of their masses.
Hence Proved.
This thought experiment shows us the power of thought. It shows us that we can also find out about some real laws governing the universe without doing any physical experiments.
