Maybe the most famous scientific experiment is Galileo Galilei's dropping objects from the leaning tower of Pisa in order to prove that all objects fall at the same rate, whatever their mass.
Many think that this experiment was never performed by Galileo and it is only a legend. To learn more about this dispute click here.
In any case, similar experiments were performed by various scientists preceding Galileo's theoretical work about falling bodies and by this disproving Aristotle's assertion that heavier bodies fall faster than light ones.
As early as 1544, the historian Benedetto Varchi referred to actual tests which refuted Aristotle's assertion.
In 1576, Giuseppe Moletti, Galileo's predecessor in the chair of mathematics at the university of Padua, reported that bodies of the same material but different weight, as well as bodies of the same volume but different material, dropped from a height arrived at the Earth at the same time.
In 1597 Jacopo Mazzoni, of the University of Pisa, reported that he had observed objects falling at the same speed regardless of weight and pieces of an object descending at the same rate as the whole.
The most notorious of those is Simon Stevin that in 1586 (3 years before Galileo) reported that different weights fell a given distance in the same time. His experiments were conducted using two lead balls, one being ten times the weight of the other, which he dropped thirty feet from the church tower in Delft. Stevin is regarded by many as the first one to perform falling bodies experiments.
However, Galileo's prominence lay in this that in 1604 he proved theoretically that falling bodies obey the law of uniformly accelerated motion. This states that all objects fall at the same rate, whatever their mass. And with this among others he established mechanics as a science and paved the way for Newton later in the century.
We do not recommend dropping lead balls and other objects from high buildings and towers since this activity can be very dangerous, unless your school has a safe facility and with teacher supervision.
Instead we suggest a few safe experiments to demonstrate the phenomenon.
1. Hold on the tip of fingers of different hands a coin and a paper disc about one meter or more above the floor. Drop both of them simultaneously. The coin will reach the floor before the paper disc. From this experiment is possible to conclude mistakenly that heavier objects fall faster.
2. Mount the paper disc on the coin and drop them together. Both object will reach the ground at the same time. The meaning of this experiment is that not the amount of mass causes falling bodies to fall faster or slower but the resistance/friction of air because air resistance is applied here only to the coin and not to the paper disc and by that we can infer that air resistance and not the amount of mass prevented the paper disc from falling faster - the same as the coin.
Experiments 1 and 2 are adopted from:
Weiss Moshe, Physics by Experimental Demonstrations, vol II, Jerusalem: Rubin Mass, 1968, pp. 208-209
3. Repeat experiments 1 and 2 with different combinations of materials, mass or shape in a vacuum chamber (if your school has one). All the dropped objects from the same height will fall at the same rate, whatever their mass because there is no air resistance.
A few links about freely falling bodies physics:
The Tower of Pisa Experiment (QuickTime Movie) - Carl Adler
Galileo's Acceleration Experiment - Michael Fowler, University of Virginia
Galileo's Law of Fall
Falling Objects - Holt, Rinehart and Winston
What is Galileo's Explanation? - Carl Martikean
Soil Experiments - Sir Charles W. Shults III, K.B.B.
Measuring the Acceleration of Gravity - SMART
Aristotelian Physics - QuarkNet, FSU
Gravity - HyperPhysics
Galileo's Battle for the Heavens - PBS
Did Galileo perform the leaning tower of Pisa experiment?
The Tower of Pisa Experiment (QuickTime Movie) - Carl Adler
The Legend of the Leaning Tower - PhysicsWeb
On Motion - The Galileo Project
Weights Make Haste: Lighter Linger - Science News
Simon Stevin Links
Simon Stevin (1548—1620), Dutch engineer and mathematician. His experiments in hydrostatics showed that the pressure exerted by a liquid is dependent only on its vertical height and not on the shape of the liquid's container, and demonstrated the principle of the hydraulic press. He probably anticipated Galileo's experiments with falling bodies. Stevin is also credited with the introduction of decimals into common usage.
Simon Stevin - The Galileo Project
Simon Stevin - The Catholic Encyclopedia
Simon Stevin's Introduction of decimals - Phill Schultz, University of Western Australia
Simon Stevin - Wikipedia
Simon Stevin, Flemish tutor of a Dutch Prince - J.T. Devreese, G. Vanden Berghe
Simon Stevin Home Page
Simon Stevin's Views on Music - Huygens-Fokker Foundation
The Museum of Unworkable Devices - Donald Simanek's Pages
Simon Stevinus - Britannica 1911
