# 121 Spring 2018 Week 10

Tuesday: Precession
Before Class

• Please see solutions for BE#6, posted on main class website. By the way, a metric ton is 1000 kg.
• I am concerned that people didn’t do better on BE#6. Also, it is evident that many students are not comfortable with units and mathematical operations like squaring numbers in scientific notation. Thus, we will take on only a few new concepts: precession, the two new kinematic equations and trigonometry. This will allow a considerable amount of time for review and practice at /home and during class. Please do your part by reviewing the solutions to both the MT#2 midterms, BE#6 the problem sets and the math competence practice test. Please get together in groups and come to office hours, and make sure you understand the concepts and processes fundamental to our studies.
• Finish PS#8 – how many students can we get to hand in this PS?
• Here is a precession video I made to explain precession. It’s likely my most well-received video to date.
• Please look over these activities on Gyroscope Worksheet. Can you try some of them?
• Please see Precession by Veritassium , a super professionally made video. You’ll let me know if it’s more helpful than my video.
• Please see: Big Picture Rotation Video that includes precession.
• See work on an inclined plane video.
• Read 7.6 on two irrelevant equations and trigonometry that you are allowed to use now.
• See Trigonometry Video , now you’re allowed to use trigonometry, but remember you can also always draw a picture if you’re not sure.
• See and then you’re allowed to use those two unhelpful (in my opinion) equations, although hopefully, you’ve realized by now that you can get along without them just fine.
• People asked to see a copy of an old final exam. I won’t do that, but I will tell you that I’ve changed the order of topics after Spring 2016, so if you go to my general class website and look at MT#2 from Spring 2016 and earlier, there are plenty of problems that have components in them, representative of what you might expect to find on the final exam.
• Please take this last survey for our class.
• PS#9 with problems from the last week of class posted on main class website, with solutions as well. Please have a look.

In Class

After Class

Before Class

• Solutions to all problem sets posted! I just added solutions for PS#8. PS#9 and solutions were posted earlier in the week.
• See video on Fuzzy Dice. This reviews the problem using trigonometry.
• Watch this video: Spinning Skater What are the forces on a skater’s arms when she is spinning very fast?
• Solving the Ladder Problem, this is from winter quarter 2016, so the number of the problem is different

See Bicycle Transmission, and do the corresponding problem on

• See video on solution for 2D inelastic collision.
• Study for the final exam! You have loads of resources – old exams, solutions, videos. Let me know how I can support you.
• I plan to keep my regular office hours next week until our exam. Please come by – bring your friends.
• PS#9 with problems from the last week of class posted on main class website, with solutions as well. Please have a look.
• I posted on the main class website, answers for the math competence practice test.
• I posted a study guide to the final exam on the main class website.

In Class: