## The Little Vulgar Book of Mechanics (v0.7.0) - Force I

Last updated: February 21st 2022

Just updated this section of the book: Force I

## Force I #

"Force" is one of those concepts whose definition totally depends on context, even within "Science." In this book, whenever I say "force," it'll almost always be in the context of good ol' classical, or "Newtonian," mechanics. With that in mind, here's a basic definition: Force is the cause of motion and power.

As I mentioned, this notion of "force" was conceptualized by Newton. He brought the concept into physics (well, "experimental philosophy," which is what he would have called his work) and explained motion in terms of it. Using this concept, he made his point that all objects have a gravity, etc. So the essence of Newtonian mechanics is that we analyze the motion of shit in terms of the forces to which shit is subjected by its environment.

We'll talk about many types of forces, including: Pressure, tension, air resistance, friction, normal force, and, of course, good ol' gravity. Some forces, such as gravity and electromagnetism, act on objects without having to physically touching them. We call this type of force "non-contact force."

You are probably in some type of building right now. Picture the internal structure of the building. There are some columns supporting some weight and shit. Or, just picture anything that's under pressure, without any motion. We call this a "static" force. Tension, torsion, and compression are common instances of "static force." So that's an additional categorization of forces: "static" vs. "dynamic."

After you take a shower, and get dressed, etc. and you go and hang your towel somewhere, what do you have to do in order to achieve this? You have to make sure to balance the combination of gravity, friction, etc. so that the towel stays in place and doesn't fall off. You are dealing with static forces there.

Force has a computable meaning, with units and everything: The aptly-named Newton. One famous derivation of it is based on mass and acceleration: F = ma. In programmer speak: force = (mass: number, acceleration: number): number => mass * acceleration. Give me a mass, and an acceleration, and I'll give you the force, by simply multiplying them. This equation expresses "Newton's Second Law of Motion."

Do you notice anything missing in the above program? Better types, obviously. But, specifically: Is force really just a number?

Apparently, modern physicists define the whole of Mechanics in terms of energy, momentum and "action" (the integral of energy with respect to time). We may adopt that framework for certain explanations. But we'll never just "leave Newtonian mechanics behind" or something. That's not how builders work. We build shit. If Newtonian models and concepts help us build shit that works, there's no reason to drop them.

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