Aristotle and Galileo had opposing views on motion. Aristotle believed motion was either natural or violent, and considered the four elements as objects' proper places. Galileo disagreed and proved through experiments that all objects accelerate at the same rate in free fall, regardless of mass. He showed projectile motion follows a curved path under gravity, while Aristotle claimed objects move in straight lines. Their differing perspectives significantly advanced the scientific understanding of motion.

1. ARISTOTLE
VS
GALILEO

2. MOTION
• Is the movement or change in location of an object over
time. It is often described in terms of direction, location,
and speed.

3. ARISTOTLE AND GALILEO WERE TWO OF THE MOST IMPORTANT
HISTORICAL FIGURES IN PHYSICS. THEY MAY HAVE HAD OPPOSING
VIEWS REGARDING MOTION, BUT THEY BOTH HELPED SCIENCE
PROGRESS.

4. ARISTOTLE
• Classified motion as natural and violent.
• Considered the four elements --- earth, water, air, and fire--- as
the proper places
• He also categorized Natural Motion in terms of direction straight
up, straight down, and circular (e.g., motion of celestial bodies)
• Violent Motion – an imposed motion either by pulling or
pushing.

5. GALILEO
• “A motion is said to be uniformly accelerated when, starting from
rest, its speed receives equal increments in equal times”
• Forced by the Church to give-up working on astronomical
matters, Galileo returned to his experiments on the laws of
motion.

6. FREE FALL
• Is a type of motion wherein no other factors aside from gravity
influences the acceleration of an object.
• How is this explained by Aristotle and Galileo?

7. ACCORDINGTO ARISTOTLE
• Aristotle used a piece of paper and a coin in a thought experiment to
explain free fall. According to him, if you drop a piece of paper and a coin
from the same height at the same time, the coin would fall faster and hit the
ground first because it was heavier. One disadvantage of using thought
experiment is that many extraneous factors that can affect the results are
set aside. In this example, the masses of the two objects were used as bases
in predicting the result. One important factor was surface are. Since the
paper had a bigger surface area, it would have greater air resistance which
would make it fall slower and hit the ground at a later time compared to the
coin.

8. ACCORDING TO GALILEO
Galileo disproved Aristotle's idea of free fall. The problem was, Galileo did not
have a vacuum to verify his claim.
Galileo wanted to prove that the rate of fall or acceleration of an object is
independent of their mass. To test his hypothesis, he simultaneously dropped
a cannonball and a musket ball with different masses from the leaning tower
of Pisa. He discovered that both balls had the same acceleration.

11. PROJECTILE MOTION
• Projectile motion is a form of motion experienced by an object or
particle (a projectile) that is thrown near the Earth's surface and
moves along a curved path under the action of gravity only (in
particular, the effects of air resistance are assumed to be
negligible).

12. ACCORDING TO ARISTOTLE
• A cannonball when fired from a canon moves in a straight
horizontal line because of a force that made it move called
impetus. When the cannonball loses this impetus, it will fall to
the ground abruptly as shown in the vertical path directed to the
ground. (refer to figure 3.3a.)

13. ACCORDING TO GALILEO
• But Galileo had another thing in mind. He explained that when
you fire a canon, the cannonball moves in a two-dimensional
motion as seen in figure 3.3b. The curved/parabolic path taken
by the cannonball indicates that while the cannonball is moving
forward, gravity pulls it down.

15. MOTION GRAPHS
• Although the quantitative description of motion is accurate, it
sometimes fails to give an observer a clear picture on how
motion occurs. That is why motion graphs are needed for easier
interpretation.

16. Distance(m)
Speed(m/s)0 0Time (s) Time (s)

17. Position(m)
Position(m)0 0Time (s) Time (s)

18. Velocity(m/s)
Velocity(m/s)0 0Time (s) Time (s)

19. Acceleration(m/s)
Acceleration(m/s)0 0
Time (s)
Time (s)

20. Position(m)
Velocity(m/s)
Acceleration(m/s)
Time (s) Time (s)Time (s)
0 00