Galileo and Inertia
When many people think of the "Concept of Inertia" they think of Isaac Newton and his three "Laws of Motion" but in actuality another philosopher envisioned the concept. Aristotle believed that objects at rest remained at rest unless a force acted on them, but that objects in motion did not remain in motion unless a force acted constantly on them. But Galileo Galilei later proved that the analysis of Aristotle was incorrect because it failed to account properly for a hidden force: friction. Therefore Galileo is the actual founder of the "Concept of Inertia." He came upon the theory of inertia by considering four different scenarios involving a round object and two inclines.
The first scenario was comprised of two identical inclines right up against each other; he imagined these inclines were so smooth they had no friction. Then he envisioned a ball that was also so smooth that it had no friction, placed at a certain point on the inclines. Once the ball was released, it would travel down the first incline and when it reached the second incline it would travel up it the same distance it traveled down the first one.
In the second scenario Galileo wondered what if the second incline was not as steep. When the ball is released from the steep incline it again rises to the same height on the second incline from which it was released. Now, however, the ball has to roll a greater distance up the second incline before it comes to a stop for an instant at the top of its motion. Therefore, it takes more time for the ball to roll to a stop on the second incline before it begins to roll back.
The third scenario was very similar to the second by the fact that it focused on the same concept of decreasing the steepness of the second incline. Galileo demonstrated that if the second incline was even steeper the ball would roll for an even longer time on the incline before coming to an even longer pause before...