### Introduction To Section 3

### Section 3 Assets

- Section Assets Pack
- Previous section project, for Magnus Effect

### Section Notes

### Unstable Rotation In Unity 5

- The limitations of spinning objects in Unity 5.
- Why unstable rotation doesn’t evolve.
- How to model unstable rotation in game physics.

### Introducing Inertia Tensors

- Roughly what is an inertia tensor (
**I**)? - Unstable intermediate axis
- How Unity Calculates
**I** - Calculate
**I**for your phone - Predict it’s unstable axis

### Calculating Moment Of Inertia

- How about if two axis are equal?
- Try it with a spinning cylinder.
- Calculate the moment of inertia.
- Render vs. collider mesh influence.

### Parallel Axis Theorem

- NOT the same as Intermediate Axis Theorem.
- How to calculate I for compound objects.
- Think of a discus thrower.
- Parallel Axis Theorem - Wikipedia,the free encyclopedia

### “Newton’s Laws Of Rotation”

- A recap of Newton’s laws of motion.
- How these relation to rotation.
- Important differences.
- Why we’re jumping in the deep end!

### Applying Torque To Rigidbodies

- How to use Unity’s
**AddTorque()**method. - How Inertia Tensor affects rotation.
- Comparing the rotation of two objects.

### Vector Cross Products

- What a cross product is.
- Why they are so useful.
- Using WolframAlpha to calculate.

### The Magnus Effect

- What the Magnus Effect is.
- How we can approximate ball flight with it.
- Using
**Vector3.Cross**in Unity.