Physics extends well into your everyday life, describing the motion, forces and energy of ordinary experience. In actions such as walking, driving a car or using a phone, physics is at work. For everyday living, all the technologies you might take for granted exploit the rules of physics.
Simple Mechanical Devices
An easy place to see physics in action is with a simple lever – most easily observed at a park. Levers come in three flavors, each with varying fulcrum locations. They serve to magnify force, lessening the effort needed to move an object on the opposing end. A simple “see-saw” at a park consists of a lever (the locations for sitting) and the fulcrum (placed in the middle). The two opposing forces counterbalance each other, creating a smooth ride through the air. At the same park you'll see a slide, a device that combines the stairs going up with the slide going down, both examples of inclined planes. The inclined plane eases the effort of climbing by spreading it over a longer distance. The smooth slide returns you gently to earth, slowing the influence of gravity just enough to make it fun.
Transportation and Newton's Laws
The transportation industry is no stranger to the manipulation of everyday physics. Cars and trains utilize the wheel, which provides a smooth, steady motion. Newton's laws of motion are at work as mechanical force and acceleration, action, reaction and inertia. Airplanes take it one step further, allowing lift as well as forward momentum. They manipulate physics – much like birds – by creating lift through wing shape as well as the wing’s angle – both of which serve to alter airflow.
Relativity and Modern Communications
Physics is all relative. This theme resonates through Einstein’s special and general theories of relativity. Einstein's work is crucially important to GPS in your phone, for example. It takes radio signals from several satellites orbiting the Earth and calculates your location accurate to several centimeters. Because the speed and height of the satellites alters the signal very slightly, the smartphone adjusts the results using Einstein's theories. Without a helping hand from relativity, GPS would be far less accurate or useful.
Physics and Biology
Even as you read this sentence, physics is at work. The eyes evolved in many species – through several examples of convergent evolution – harnessing the electromagnetic spectrum. The ears hear sounds which occur through the movement of air molecules. And the chemistry that drives all of biology depend on the physics of energy and molecules. Every day, for example, plants absorb sunlight, water and carbon dioxide, creating glucose and releasing oxygen as a byproduct.