All the technology we rely on, from cars to wisdom phones, was created using physics. You don’t need to know the science to use these things. But a good round person should understand at least some of the key concepts – together with some music, art, history and economy. Robert Heinlein said everything in Time enough for love:
“Man should be able to change diaper, plan an invasion, slaughter pig, connect a ship, draw a building, write a sonnet, balance accounts, build a wall, set up bone, comfort the dead, take orders, order, cooperate, cooperate, act alone, resolve equations, analyze a new problem, throw fertilizer, program computer, cook delicious food, effectively fight, gallant dying.
So, not to be insects, here are my top five physical equations that you should know.
1. Second law of Newton
I’m sure you’ve seen this one before-it’s over 300 years old, and it’s popular for scientific memes and t-shirts. It says the net force on an object equals its mass (m) times acceleration (a). But what does that really mean? It’s all about interactions – as when you kick a football ball or drop a water bottle on the floor.
Newton’s second law says that we can describe these interactions with the concept of “strength”. And what do forces do? The net force on an object changes the movement of the object. But wait! There are much better things in this simple -looking equation.
See those arrows above F and a? This indicates variables that are vectors, which means they contain more than one information. For example, if someone asks you to “socially distance” you at 1 meter, where would you arrive? Who knows? You could go 1 meter east or west or 39 degrees from the north. The distance by itself is not the full story; You must also specify direction. This applies to both forces and acceleration. Other amounts (such as mass or temperature) have no direction. We call those scalar values.
Newton’s second law is super useful, but strangely, people don’t seem to believe it. The frequent misunderstanding is that a constant force makes an object move at a constant speed. What this equation says, rather, is that if you press an object with constant strength, it will continue to accelerate.
