A Brief History in Physics Honors Physics - Introduction to Free Fall

What Makes Things Move? “Impetus” Aristotle 384 – 322 B.C.

Why Do Objects In Motion Slow Down? “They get tired.” Aristotle 384 – 322 B.C.

Why Do Objects Move Toward the Earth? “Objects yearn to be reunited with the earth.” Aristotle 384 – 322 B.C.

Why do objects actually fall?

The birth of modern physics Galileo Galilei 1564 – 1642 Astronomer Physicist Mathematician Philosopher Engineer Many many contributions

Many contributions.. Inertia Kinematics Thermoscope Law of falling bodies Improved the telescope Simple harmonic motion Parabolic trajectory of projectiles Publicly supported heliocentric system Enforced the scientific method by testing hypothesis via experiment

How does a ball fall downward? Does position increase, decrease, or remain constant? Does velocity increase, decrease, or remain constant? Does acceleration increase, decrease, or remain constant?

How can we measure it? Piza

Gravitational field “Acceleration due to gravity” Denoted as “g” Uniform acceleration directed toward the center of the Earth g = 9.81m/s2 + or – depending on how you analyze the problem Letting upward represent the + direction and downward represent the – direction is a bit more conventional

Do heavier objects fall faster? Compound body thought experiment

Why don’t objects speed up indefinitely?

Measuring freefall Pisa

Apollo 15 Commander David R. Scott August 2nd, 1971 Hammer vs. feather Absence of air resistance (in a vacuum) https://www.youtube.com/ watch?v=5C5_dOEyAfk

So how fast can objects fall? Felix Baumgartner, Oct 14, 2012 39,068.5 meters / 128,177.5 feet / Mach 1.25

https://www.youtube.com/watch?v=rzaQ4r55u6w

Let’s Physics The speed of sound is 340.29m/s. How long did it take Felix to break the sound barrier and how far did he fall? Note: Use g = 9.81m/s2 “g” actually varies as he falls.. Time elapsed = 34.9s Displacement= -5902m