Aristotle, Copernicus, and Galileo on Motion

Natural Motion

Motion occurring without external forces, like falling. coined by Aristotle

Violent Motion

Motion resulting from external forces pushing or pulling. coined by Aristotle

Resting State

The assumed proper state of objects without external influence in Aristotle's time

Copernicus' Theory

Earth and planets orbit the sun, not vice versa.

Controversy of Copernicus

his idea of motion in space was extremely controversial at the
time, because most people believed that Earth was at the center of the
universe.

Galileo's Contribution

demolishing the
notion that a force is necessary to keep an object moving.

Friction

Force opposing motion between touching materials.

Galileo's Ball Experiment

that a ball rolling on a smooth horizontal plane has almost
constant velocity, and if friction were entirely absent, the ball would
move forever.

Newton's work showed what about objects on Earth?

showed that objects on Earth move with Earth as Earth
moves around the sun. The law of inertia also shows that objects within
moving vehicles move with the vehicles.

Secret Publication

Copernicus worked on his ideas in secret to avoid persecution. At the
urging of his close friends, he published his ideas.

Natural motion during Aristotle's time

thought to be either
straight up or straight down: It was "natural" for heavy things to fall and
for very light things to rise.

Galileo's Friction Insight

argued that only when friction is present—as it usually is—is a
force needed to keep an object moving.