**Day 1:**HEY! might not be a bad idea to start reviewing old problem sets and exams to prepare for the final exam!

__Conserving Angular Momentum, when Sum of the Torque = zero__

- Angular momentum =
*I*alpha,*like linear momentum = m*v*kind of* - Torque
=**SOMETIMES***I * alpha*, as stated above in rotational dynamics. Torque= rate of change of angular momentum*ALWAYS* - For instance if Torque = zero, then angular momentum is conserved (just like we conserve momentum if there’s no outside force)
*it doesn’t mean that alpha = zero, like acceleration = 0 if the sum of the forces = 0, Think of the spinning skater pulling in her arms, yielding a positive angular acceleration.*

**Before Class**

- Collect PS #7,
- PS#8 is posted please read through it.
- Read 10.5 in your text and check out example 10.14
- Please watch this video on torque = time derivative of angular momentum
- Please see video on Coriolis Effect , made by students from Fall, 2014
- PS#9 due next week has been posted. Please take a look at it.
- I posted my summary and reflection from your week 8 feedback on the main webpage

**In Class:**

**Day 2:**

How can a point mass (with no radius and no moment of inertia) have angular momentum? It all depends on the *impact parameter!!*

**Before Class**

- Angular Momentum of a Point Mass
**Bullet Hits Block Veritassium**- Please read through PS#8
- Solutions to MT#2 posted on main website. Please make sure as soon as possible that you would get all these problems correct if you were to encounter them again.

**In Class**

**After Class**

**Day 3: More on how Torque = rate of change of angular momentum**

**Before Class**

- Please see the video on angular momentum: Wheel Kick and Figure Skating
**Veritassium Which Block Goes Higher?**

**In Class**

- Big Exam #6 – Solutions posted on main class page

**After Class**

**Day 4:**

Precession:

Torque is rate of change of angular momentum so dL = (torque)*dt. However, angular momentum is a vector, so you also need torque to change the *direction* of angular momentum.**Before Class**

- Please see Precession by Veritassium
- read 10.8 in your text about precession.
- Optional: I made this video on precession. It’s long and slow, but it has 2700 views, so some people find it helpful: Pete’s Precession Video
- Rotational Big Picture
__Explanation of Veritassium Bullet Problem____See solutions for BE#7__

**In Class**

- Angular momentum and Gyroscopic stability. We have some cool demos for this.
- Why must we spin frisbees or footballs to make them fly stable? What is counter steering on a motorcycle?
- How is this related to precession?

**Friday. You have until midnight tonight to post your link on the website for full credit.**