# 121 Winter 2019 Week 7

Monday Washington’s Birthday Observed. No classes at Poly

Tuesday we look at a rotational system

During Class

• A day at the races, racing rolling downhill!

Wednesday
We look at the parallel axis theorem and consider how it can make a problem easier to solve.

Before Class

• I think the most effective way to learn is to work in groups with other students. If for some reason, this isn’t working, consider trying out the free tutors provided by Cal Poly Physics Department. Link to the learning center is on the main class website.
• Please watch this review video of rotation: Big picture rotation! You will notice two references to precession (that we haven’t covered yet) from 5:11 – 6:00 and and from 9:08 – 9:24 that you may find interesting, but you are not responsible for until the final exam. Likely, we’ll revisit this video at the end of the quarter, but it’s also a very good review right now. You’ll have to tell me during class if this review was a good idea, and if I should remake it without these references, or if this preparation is fine.
• Watch
• Please read 6.2 Center of Mass, this is important, and there’s no video on it, so I recommend you read this short section.
• Make video for center of mass.
• Please read 6.3 Parallel Axis Theorem
• Please take this short Survey #6
• Does a feather really fall the same as a bowling ball in a vacuum? See (optional) Human Universe do it.

Thursday

Before Class

MT#2 Monday! Some more study resources:

During Class

• Discussion, demos, preparation

Ignore below this line**************************************************

Between yesterday’s question “where do you ‘weight’ more – equator or north pole?” and today’s “how do you win a Tug-O-War?” what’s coming to me is student resistance to bust forward with a method until they have a plan toward the solution. Again, I’m asking you to go forward with a plan before you have a plan to the solution. Sometimes we can’t see a plan until we’ve explored it – like needing to walk down a path for a while before knowing where it will bring you. Please try to notice this resistance, and make a point of doing something without knowing if it will work. Generally, so much in life requires that you risk wasting your time on something that doesn’t work. If you’re curious about me, you could read about some of the failures I’ve had that have brought my life value and allowed me to move in a direction I wouldn’t have known about: Guateca, or My Home.