# Spring 17 Mechanics Week 9

Monday, Holiday

Tuesday
Before Class

• See video on Slack Lining. Is this how you solved the problem?
• Watch Statics and do problem #1 on PS #8.
• Check out PS#9, just posted.
• There’s a small amount of new material today, so please take a look at the solutions I posted for MT#2 (as well as comments on the extra problem #5) and Solutions to PS#7 on the main class website. I spent several hours on it, so please take a look and tell me if my efforts were worth it.
• Please see: Explanation of Veritassium Bullet Problem
• See your feedback and my response from Thursday’s class, posted on main class website.

During Class

This week, we review a little and also study the final topic: How torque is the rate of change of angular momentum, and how they are both vectors, so when torque is perpendicular to angular momentum, torque doesn’t increase or decrease angular momentum. Instead, torque causes the angular momentum to change direction. This is precession.

Wednesday we review a little to get back in shape from the week gone by. Be ready to finish your projects.

Before Class

During Class

• Make some time to discussion projects.
• 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?

Thursday: We look at angular momentum as stability.

Before Class

• Here is a precession video I made recently to explain precession. It’s likely my most well-received video to date.
• Please do problem #3 in PS #9, Due next Monday in class, Get a wheel and try it out.
• Group project is due Friday (tomorrow). Please post the website for your youtube video – make sure it’s public so I can see it.