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Galileo's Leaning Tower of Pisa Experiment Explained
It was the Italian scientist Galileo Galilei who performed the famous experiment that proved that the acceleration at which objects fall is the same irrespective of their mass. That experiment is known as Galileo's Leaning Tower of Pisa Experiment. Its result was a direct violation of Aristotle's theory of gravity which assumed that objects fell at a rate that is directly proportional to their mass.
Archimedes' prediction of the experiment (left) and Galileo's measurement (right), Wikimedia Commons CC-BY-SA-3.0.
Although it's still not clear if this famous experiment was conducted in reality or if it was a thought experiment, Galileo Galilei is said to have conducted it around 1589. He dropped two spheres of different masses from the top of the Leaning Tower of Pisa because he wanted to demonstrate that the objects would fall at the same rate independent of their masses. Indeed, the two spheres hit the ground at the same time, supporting the idea that objects fall at the same rate regardless of their masses. This was again proven to be true years later when the Apollo 15 astronaut David Scott dropped a hammer and a feather from the same height on the Moon and they hit the Moon's surface simultaneously. Before Galileo's experiment, Aristotle's theory of gravity was widely believed, which stated that objects fall at a rate that is proportional to their masses. Quite a while after Galileo's experiment, he provided a theoretical explanation for this phenomenon.
Galileo's falling body experiment performed by David Scott on the Moon in which a feather and a hammer reach the surface of the Moon at the same time, StudySmarter Originals.
Galileo's ball drop thought experiment
Galileo's ball drop thought experiment was crucial in understanding the effect of acceleration due to gravity on a falling object, and it ended the debate once and for all. It proved that Aristotle's theory of gravity was incorrect. Let's look at what Galileo thought about!
Imagine standing on top of the Leaning Tower of Pisa. Assume heavier bodies fall at a higher rate than lighter bodies. You now drop two balls of different masses from the top but there's a catch: the balls are connected by a string. According to the assumption, the heavier ball would fall faster than the lighter ball, so the string would be pulled taut: the tension of the string is pulling on the heavier ball which should therefore reduce its acceleration.
All objects fall at the same rate, StudySmarter Originals.
But this would mean that if we drop the heavy ball without any attachment, its acceleration would be greater than the system where two balls are attached. This contradicts our initial assumption where we say that the heavier body will fall faster: the whole system should fall faster than any individual ball. Thus, our assumption is false: the only possible explanation is that all bodies will fall at the same rate regardless of their masses.
In this thought experiment, we assume that the objects are in free fall, which means that we do not take air resistance into consideration.
Galileo's theory of gravity
Galileo's theory of gravity states that all objects fall at the same rates irrespective of their masses.
Galileo determined through his experiment that the items fell with the same acceleration, verifying his prediction and disproving Aristotle's theory of gravity, which states that objects fall at a speed proportional to their mass.
Galileo's theory of motion
We've all heard about Newton's first law of motion but did you know that Newton's first law of motion was originally proposed by Galileo?
Galileo's law of inertia states that an object will continue to move in a straight line at constant speed unless an external force acts on it.
He came upon this conclusion during one of his experiments. He discovered that if you let a metal ball slide down a ramp and then slide up onto another ramp, the ball will always rise to its initial vertical height irrespective of the inclination of both the ramps. This led him to think that if the inclination of the second ramp was zero the ball would keep rolling forever since it would never reach its initial height. Many years later, Newton would develop his first law of motion on the very same principles.
Galileo's experiment provided inspiration for and supported his law of inertia, StudySmarter Originals.
Galileo and acceleration
Aristotle had claimed that force causes speed, but this was again disproved by Galileo who claimed that force causes acceleration. This was again derived from his falling bodies experiment. He predicted that the speed of bodies falling toward the earth is constantly increasing. This increase in velocity, also known as acceleration, is caused due to the force of gravity. We can prove this with an experiment.
When a ball is dropped from a height, it can be experimentally determined that the distance it travels in its first second of descent will be smaller than the distance it falls in subsequent seconds of descent. This means that its speed is constantly increasing. This increasing speed is caused by nothing other than gravity, which is a force, bringing us to the conclusion that force produces acceleration.
Galileo's Leaning Tower of Pisa Experiment - Key takeaways
- Galileo Galilei conducted the falling bodies experiment to disprove Aristotle's theory of gravity.
- Aristotle's theory states that objects fall at a rate that is proportional to their mass.
- Galileo's theory of gravity states that all objects fall at the same rate regardless of their mass. This is still accepted as true to this day.
- Galileo explained his findings with a thought experiment involving two balls connected by a string.
- Galileo's law of inertia states that an object keeps moving in a straight line at a constant speed until an external force acts on it.
- It is the same as Newton's first law.
- Free fall does not take into consideration the frictional force of air resistance.
- Galileo discovered that force causes acceleration and not speed.
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Frequently Asked Questions about Galileo's Leaning Tower of Pisa Experiment
What did Galileo discover in his experiment on the Leaning Tower of Pisa?
Galileo concluded that all objects fall at the same rates irrespective of their masses.
How did Galileo prove that all objects fall at the same rate?
Galileo experimentally proved this by dropping a light and a heavy ball from the Leaning Tower of Pisa. He theoretically proved it by imagining to drop a light and a heavy ball connected by a string.
What did Galileo do to experiment with gravity?
Galileo performed an experiment by dropping two balls of different masses from the top of the Leaning Tower of Pisa. He also rolled balls over inclines to see how far they came, inspiring his law of inertia.
What experiments did Galileo do to test and support his ideas?
Galileo performed an experiment by dropping two balls of different masses from the top of the Leaning Tower of Pisa, testing and supporting his idea of constant gravitational acceleration.
How did Galileo disprove Aristotle about objects in motion?
Galileo performed an experiment by dropping two balls of different masses from the top of the Leaning Tower of Pisa. He found that the heavy ball hit the ground first, but only by a little bit. Both balls reached nearly the same speed.
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