**Monday: Angular Dynamics and Statics.**

Master the use dynamics (vector sum of the torques =

*I * alpha*) just as you did for force and acceleration in linear motion

Augment your use of Work-Energy Theorem with rotational kinetic energy.

**Before Class:**

- I added some comments to MT#1, on main class website.
- I added one more problem to PS#4
- Watch the videos: Torque and the Lever
- Read 4.5 Introduction to Statics
- Then watch the video about the standard diving board problem
- Did you know that studies indicate texting costs students an average of half a letter grade in their classes. Should we do something about this? NPR story about cell phones and classes

**In Class**

BIG EXAM!

Collect PS#4

**After Class**

**Tuesday**__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**

- Check out our Facebook page for communication and organizing meetings.
- Please watch this video on torque = time derivative of angular momentum
- Please read 4.6 Introduction to Angular Momentum.
- There’s only one physics video, so I want you to be aware of one more thing: just like F=ma, for rotational problems we use
*Torque = I*alpha.*Please identify in your problem set which questions involve this*Rotational Dynamics*. Then, please describe a*protocol*for rotational dynamics (Forces) that is a rotational analogue of our*protocol*for linear dynamics. - I ask you to be prepared to “think with your hands”. Please see this NPR article that shows students who take notes by hand retain more information than students who type notes into a computer. My inference (which may not be correct) is that if you did neither, then you’d retain even less.
- Please see PS#5

**In Class:**

Dropping kids on merry-go-round, barbell spinning in space

**After Clas****s**

we will examine an object that circulates into a circular path… like how the moon doesn’t travel in a straight line because the attractive force of gravity between the earth pulls the moon into a circular path.

**Wednesday,** we look at centripetal acceleration. PS#5 Posted! Please take a look!

**Before Class**

- SO! when you watch videos, do you answer the questions to get them done and move on, or do you actually read the comments for a wrong or right answer? I find this information very important and put it there because it confronts common misunderstandings and/or mistakes students make. Please give it a try and let me know what you think.
- Watch derivation of Centripetal Acceleration and how to use it. Make sure you can do this for Big Exam.
- Read 5.0 Centripetal Acceleration
- If we look at the earth spinning in space, we might notice that there’s nothing making it turn… that it is free of external torques. We might consider that we’d then look at the earth through the lens of
*angular momentum.*What could we learn? Please see video on Coriolis Effect made by students from Fall, 2014. Look for a number of things:- Do we understand the Coriolis Effect?
- Do we see the value in looking through the angular momentum lens?
- Are we getting ideas for how we’d like to make our final video project?

**Thursday:** we look at universal gravity and the inverse square law.

- Please read 5.2 inverse square relationship
- See video on Universal Gravity and Inverse Square Law
- Read 5.1 Universal Gravitation that I’ve shamelessly plagiarized from OpenStax… uh, you’re allowed to plagiarize OpenStax, that’s what they are there for.
- Watch video: There’s No Such Thing as Centripetal Force, or Centrifugal Force
- Veritassium music gravity video
- Optional: Remember that article that I wrote about our physics class that you didn’t want to read? Well, it published. Here is the free .pdf, and here is the online version with live links that requires a subscription (but you can access for free from Cal Poly). Even if you don’t want to read it, you can send it to anyone who may wonder what our physics class is like.