Principles of Aeronautics:
How Things Work
Most people know Sir Isaac Newton for his discovery of gravity, which is thought to have been triggered when he watched an apple drop from a tree. But Newton was also responsible for laying down the fundamental laws of the physical universe: the principles that describe not only how things work but why. These principles are his laws of motion, and they built on the work of great scientific minds who came before him.
Newton was born in Lincolnshire, England, in 1642, only a few years after the death of Galileo Galilei. He showed no particular talent for farming (his family's line of work), but a true genius for mathematics. Building on the work of predecessors such as Galileo, Copernicus, and Kepler, he laid out the principles of his laws of motion, the universal theories that tied the work of these great minds together. He once confessed, "If I have seen further than other men, it is because I stood on the shoulders of giants."
Newton was insecure, badtempered, and sometimes reclusive--not exactly the friendly figure of folklore who was charmed by the fall of an apple. But he explained the physical laws that allow us to walk on the moon and build ever more exciting amusement parks. These are the laws of motion he laid down:
The First Law of Motion: The Law of
This law governs why a driver is thrown forward in a head-on automobile accident. The car may have stopped, but the driver continues moving forward unless held in place by a seatbelt.
The Second Law of Motion: The Law of
To understand this law, imagine pushing a pebble, and then imagine pushing a boulder. The pebble has a smaller mass, and so will accelerate faster than the boulder will. Now imagine pushing a boulder with your bare hands and then imagine pushing it with a powerful backhoe. The backhoe is able to exert more force on the boulder, and so will make it accelerate faster than when you pushed it with your bare hands.
The Third Law of Motion: The Law of
Think about the bumper cars. When you hit another car, you exert a force on that car. That's not the end of it, though. Even if you hit a car that is at rest, that car is also exerting a force on you. These forces are opposite, or moving in different directions from each other.
Here's another example. When you jump up in the air, you must first propel yourself by pushing away from the earth (or in other words, pushing the earth away). You can't perceive it, but the earth responds by pushing you away from it. Both your push against the earth and the earth's equal and opposite push against you propel you into the air.
"Amusement Park Physics" is inspired by programs from The Mechanical Universe...and Beyond.