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Tiger Woods, Kobe Bryant, and Michael Phelps might seem like forces of nature, but they are nothing compared to what physicists mean when they say “forces of nature.” Tiger Woods might be able to use the law of gravity to his advantage, but the laws of gravity won’t bend even a little to help Woods score hole-in-ones.
Forces & Motion is the part of physics most clearly connected to everyday life. We throw balls, drive cars, drop things, push furniture around, and slide into home plate. Every motion of every object we see and experience is an application of the physics of forces and motion.
Motion describes the way things move: displacement, velocity, and acceleration. Displacement measures our change in position, velocity is the rate at which that position changes, and acceleration is the rate at which velocity changes. We can use displacement-time, velocity-time, and acceleration-time graphs to help us understand motion, and equations to calculate how the position and velocity will change over time. These tools allow us to describe and understand how things move.
Forces on the other hand is about answering the question: why do things move the way they do?
How can we predict motion before it happens? To do that, we need to understand pushes and pulls (that’s what a force is). There are lots of types of forces including gravity (weight), friction, tension, magnetic forces, electric forces, buoyant forces, lift, air resistance, and thrust/driving forces. We’ll need to understand the rules (or laws) that govern how they work. For example, gravity always points downwards, and buoyant forces always point up.
Lots to learn, we know, but by the time we’re done, we’ll be better diviners than Trelawney. We’ll talk about Newton’s Laws of Motion, friction, circular motion, and gravity, and we’ll get so good at solving problems we’ll be able to beat Tiger Woods at his own game—just give us a pen, paper, a calculator, and an hour before each shot to run the numbers.