 So now that we have a better understanding of what physics is, how can we actually use all of this physics? As I mentioned earlier in this video, we will learn about Newton's law of universal gravitation in the form of a mathematical equation. Now why is a mathematical equation so important to understanding physics? And why do we spend so much time learning about the equation for Newton's law of universal gravitation? Well ultimately this equation is a tool that allows us to understand and predict how gravity affects the world. Lots of things are affected by gravity, and Newton's law of universal gravitation allows us to model these effects. If we can quantify the rules that the world around us seems to follow, we can use these rules to manipulate our environment. For example, we can work out how objects fall on the earth, how ramps affect the motion of objects, how a banked track lets a vehicle go faster, how objects in space pull and orbit each other, how far away a satellite should be to be in a useful orbit, and what happens when there are multiple objects pulling on each other. These are some of the topics we'll cover in the course, but there's a big difference between understanding the concept of gravity, which is that things this mass attract each other, and knowing how Newton's law of universal gravitation works. Without a mathematical model, it's very difficult to make specific and testable predictions. But similarly, without understanding the concept of gravity, then Newton's law of universal gravitation is just an equation with some random parameters in it. We need to use both physics concepts and equations to truly understand and use physics. In the next video, we'll be introduced to the form of this equation for the first time. But keep in mind that the equation is powerful because it can explain a lot of the physical behavior we observe, and ultimately how our universe works.