Monday Washington’s Birthday Observed. No classes at Poly
Tuesday we look at a rotational system
- Please see how to solve a system of masses using dynamics
- Please read 6.1 Rotational Systems that you can find in our textbook.
- Watch Rotational Systems
- Check out the physics of the pinewood derby
- A day at the races, racing rolling downhill!
We look at the parallel axis theorem and consider how it can make a problem easier to solve.
- 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 Parallel Axis Theorem
- 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.
- See one way for Solving flywheel with hanging mass (this is the worked solution) (2 minutes)
- See a system of masses using work and friction (2 minutes)
- See a system of masses using dynamics (3.5 minutes)
- Watch solution to problem Barbell Spinning in Space
MT#2 Monday! Some more study resources:
- Matt is holding a review session again Sunday at noon by my office, 180-608.
- From Spring of 2018 (this is a 121 class and of similar difficulty as what you might expect: MT#2, MT#2 guidance, MT#2 solutions, MT#2-2 with comments.
- The rest of the exams are 141 exams and may be slightly more technically demanding than what you might expect. Try from Fall 2018: MT#2, MT#2 with comments, MT2_Solutions,
- From spring 2017 class: MT#2 + extra problem, MT#2 Solutions, MT#2 help on #1, #5
- From winter 2018: MT#2 Winter 2018, MT2_Comments, MT2 Solutions,
- I found 5 old review questions and solutions kicking around.
- From Fall 2016: MT#2, with two more (underlined) questions for greater practice MT#2 Solutions
- Want to see more? Just go to the shared curriculum website and see the old exams.
- Keep in mind two things:
- The curriculum has changed, so MT#2 from classes before Fall 2016 may be of limited value… or you will be surprised to see material we haven’t covered and won’t be on your MT #2.
- Our MT#2 may be a little different from Fall 2016 in that I may ask you to discuss some questions without solving them.
- Keep in mind two things:
- Discussion, demos, preparation
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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.