Study Guide For Gallileos first Experiment
Born in 1564, Galileo Galilei was an Italian physicist, astronomer, philosopher, and mathematician.
Around the year 1589 ( This is a A TIME BEFORE SCIENCE EXISTED ) Galileo set out to test
his hypothesis that two objects of different size and weight would hit the ground at the same time
when dropped from great heights.
The great philosopher Aristotle, had claimed that objects of greater weight fall faster than those of
lighter weight. To test this theory, it is said that Gallileo dropped a 10 pound ball and a 1 pound ball
from the top of the Leaning Tower of Pisa. A large crowd witnessed Galileo’s experiment. The 2
balls hit the ground at the same time. The evidence was overwhelming that Aristotles idea was
wrong. Gallileo concluded that heavy objects and lighter objects fall at the same rate.
An experimental result must be repeatable to be considered valid,. Scientists and students have repeated
Galileo's experiment many times, with a variety of objects.
Astronaut David Scott tried it on the moon using a feather and a hammer, since the lack of air resistance
meant he did not need items with the same basic shape.
( you can find a short movie of this on youtube ).
Gallileos Experiment:

IS A CONTROLLED EXPERIMENT where all the untested variables were kept the
same. Gallileo was testing the effect of Mass on the rate of fall. He kept the shape of
the objects the same. Dropped at the same time from the same height under the same
weather conditions. All variables were kept the same except the mass of the 2 objects
( metal balls ) which he dropped.

GIVES REPEATABLE RESULTS
experiment

ALLOWED ACCURATE PREDICTIONS TO BE MADE ( such as the prediction that a
hammer and feather would hit the surface of the moon at the same time when dropped
from the same height.

TESTED A CLAIM MADE BY AN EXPERT. Gallileo was a good scientist becaue he
was skeptical about Aristotles claim. Aristotle was a great thinker who claimed
that a heavier object would hit the ground before a lighter object
Thousands of people have repeated this
Try the interactive activities at the NOVA website. Allows you to drop the cannonballs off the
leaning tower of Pisa and do other experiments
http://www.pbs.org/wgbh/nova/physics/galileo-experiments.html
LEVI decides to test Gallileos claim that objects with different Masses fall at the same rate.
He does the following experiment:
Monday:
Drops a bowling ball with a mass of 10.0 Kg from a height of 85.0 Meters.
Levi measures the time of fall as 2.7 seconds
Tuesday:
Drops a cookie tray with a mass of 1.35 Kg from a height of 85.0 Meters
Levi measures the time of fall as 2.5 seconds.
After his one trial….
Levi reasons that the time of fall for the bowling ball and the cookie tray are so close that they are
basically the same number. He concludes that heavy objects and lighter objects fall at the same rate.
Can you find 2 mistakes in the way Levi did his experiment?