Every technology we rely on, from cars to smartphones, was designed using physics. You don’t need to know science to use these things. But a well-rounded human being should understand at least some of the key concepts, as well as some music, art, history, and economics. Robert Heinlein said it all Enough time for love:
“A human being should be able to change a diaper, plan an invasion, slaughter a pig, pilot a ship, design a building, write a sonnet, balance books, build a wall, hand over a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, throw manure, program a computer, cook a tasty meal, fight effectively, die valiantly. is for insects.
So, in the interest of not being bugs, here are my top five physics equations you should know.
1. Newton’s second law
I’m sure you’ve seen this one before: it’s over 300 years old and popular for science memes and T-shirts. It says that the net force exerted on an object is equal to its mass (m) times the acceleration (A). But what does this actually mean? It’s all about interactions, like when you kick a soccer ball or drop a water bottle on the floor.
Newton’s second law says that we can describe these interactions with the concept of “force.” And what are the forces doing? The net force exerted on an object changes the motion of the object. But wait! There’s a lot of other cool stuff in this simple equation.
See these arrows above F And A? This indicates variables that are vectors, meaning they contain more than one piece of information. For example, if someone asks you to “social distance” 6 feet, where will you end up? Who knows? You can go 1 meter east or west or 39 degrees north. Distance by itself is not a complete explanation; you must also specify a direction. This is true for both forces and acceleration. Other quantities (like mass or temperature) have no direction. We call these values scalars.
Newton’s second law is very useful, but strangely people don’t seem to believe it. The most common misconception is that a constant force makes an object move at a constant speed. Rather, what this equation says is that if you push on an object with a constant force, it will continue to accelerate.
