Installing Unity and starting a new project in Unity
  1. You can download the latest version of Unity for free by visiting http://unity3d.com.
  2. Start Unity and watch the Getting Started video in the first screen to learn all about what you need to know to get started.
  3. Click the Projects tab and then the Create button.
  4. Name your project Movement and then specify where you want it saved. Also, select 3D to create a 3D project.
  5. Click the Create project button.
For more help getting started, go to the Unity Interface and Essentials webpage for many detailed video tutorials on how to get started with Unity.

What are physics engines?
Watch these three videos as an introduction to video game physics engines.
http://youtube.com/watch?v=jI7n5GAix98
Watch this video on the History of physics game engines.
http://youtube.com/watch?v=rpeANrZdSX8
This video discusses current trends in video game physics.
http://youtube.com/watch?v=yIqUiDBM434