I need you to setup a project

You can think of Mix as your Elixir Utility Belt. It builds your projects, runs tasks for you, runs your tests, installs packages - a fascinating tool. That comes later - right now open up your terminal and navigate to a directory where you can save your work.

This is one of many projects you'll be creating so make a redfour directory on your drive somewhere.

mix new physics

You should see some stuff splash on your screen:

* creating README.md
* creating .gitignore
* creating mix.exs
* creating config
* creating config/config.exs
* creating lib
* creating lib/physics.ex
* creating test
* creating test/test_helper.exs
* creating test/physics_test.exs

Your Mix project was created successfully.
You can use "mix" to compile it, test it, and more:

    cd physics
    mix test

Run "mix help" for more commands.

As you can see Mix created the skeleton of an application for you. There are different ways to think about this structure - as a package that's part of a library or as an app in its own right. Right now don't worry about it we'll get to that later.