All the technology we depend on, from vehicles to mobile devices, was crafted using the principles of physics. While you don’t have to grasp the science to utilize these tools, a well-rounded individual should at least be familiar with some fundamental concepts—along with an appreciation for music, art, history, and economics. As Robert Heinlein articulated in Time Enough for Love:
“A human being ought to be capable of changing a diaper, planning a military campaign, preparing meat, navigating a ship, designing a structure, composing a poem, managing finances, building a wall, setting a bone, providing comfort to the dying, following orders, giving orders, collaborating, acting independently, solving equations, analyzing new challenges, dealing with refuse, programming a computer, cooking a delicious meal, fighting effectively, and dying honorably. Specialization is for insects.”
To avoid being insect-like, here are my five essential physics equations you should familiarize yourself with.
1. Newton’s Second Law
You’ve likely come across this concept before—over 300 years old and a staple in science memes and merchandise. It asserts that the net force acting on an object is equal to its mass (m) multiplied by its acceleration (a). But what does that truly entail? It’s all about how things interact—like when you kick a soccer ball or drop a water bottle onto the floor.
Newton’s second law allows us to articulate these interactions through the idea of “force.” And what role do forces play? The overall force acting on an object alters its motion. But there’s even more fascinating information contained in this seemingly simple equation.
Notice the arrows over F and a? They signify that these variables are vectors, meaning they encompass multiple elements of information. For example, if someone instructs you to “maintain a distance of 1 meter,” where would you end up? It’s ambiguous—you could position yourself 1 meter east or west, or even at 39 degrees from north. Distance alone doesn’t tell the full story; direction is also essential. This principle holds true for both forces and acceleration. Other quantities, such as mass or temperature, do not have direction and are referred to as scalar values.
Newton’s second law is incredibly beneficial, yet strangely, many people seem to misunderstand it. A prevalent misconception is that a steady force results in an object moving at a constant speed. What this equation actually conveys is that if you exert a constant force on an object, it will continue to accelerate.
