Spring 17 Mechanics Week 9

Monday, Holiday

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.
  • read 10.8 in your text about precession.
  • See video on how gyroscopes can stabilize boats.
  • 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.
  • ANNOUNCEMENT: Late videos will be counted for half credit. Please remember that this class is not graded on a curve. It is not competitive. Therefore, if you have watched all the videos on time, this will not negatively impinge your grade. Additionally, watching the videos on time has made you a stronger student and is likely reflected in your performance on exams. I apologize for this change in the curriculum, and I recognize that changing the syllabus at this time can be seen as unprofessional. I made this change because I’ve recently become aware that I have this information accessible to me. The intended result is that students will be more prepared for class for the last week (because each class draws on all the past material, not just the previous night’s), and that students will gain important information for the final exam that they may have otherwise missed. However, it’s also possible that this change will result in fewer students watching videos on time for the last week. I’ll be grateful for your feedback of how this change affected your physics experience. I welcome your perspective in this and any other policy, but I’d prefer not to use class time to discuss it. We have valuable things to learn.

In Class

  • What is precession?

After Class

Come to the Concert:
Winds concert June 3 in Harman Hall 8 PM

Post Video Project by midnight Friday night.
Study for final exam? Midterm #2 for Spring 2016 and before had component questions on them. You can access these older classes through the “all classes” website linked to our main class website.