141 Winter 2018 Week 4

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Monday : Friction!

Before Class

During Class

  • Big Exam #3

Tuesday: Review for Midterm.
Before Class

  • View Big Picture of Mechanics to get an overview of the first 4 weeks of mechanics.
  • Solutions for PS#2 sliding down a curved ramp question. I also go over some calculus that may be interesting here. This is from a past class, so the numbers are different.
  • Review how I solve the Ballistics Pendulum Video from an old problem set.
  • This is a slightly different version of the accelerating car, but try this video out if it helps you understand Powerful car accelerating I reference a question from the problem set but this is an old video and I didn’t assign this question this quarter. Thus is is all the more important that you learn from the video.
  • Study for Monday’s midterm!: Take MT#1 Fall 2017, MT#1 from Spring 2017 under test conditions: 50 min. Do the whole thing, It’s great to do it with your fiends, but pretend it’s an exam with no talking for the entire 50 minutes. Then you can compare answers afterwards.
  • After you finish the Practice MT#1 (above), please see MT#1_With_Comments from Fall 2017, and
    my feedback from Spring 2017. Then address the questions again to see if you can improve.
  • Solutions posted for PS#3. I updated the solutions at 10:55 today, Tuesday.

During Class

  • How fast can you throw a ball?
  • Prepare for MT#1

After Class

  • Make sure you see the review videos before next Monday (when we take MT#1).
  • If you want to do more questions to study for the midterm next week, you can access old classes on my sharedcurriculum website.I adopted the parallel pedagogy for Fall, 2015, so the tests before that will not be the same material as our present curriculum.

Questions about midterm:
– The midterm covers everything we’ve talked about in class, saw in videos, or had in assigned readings (including friction). In short, if you’ve been exposed to it though the class, then please expect that it could be covered on the exam

What about “smart” calculators? You are not allowed to use calculators that graph or can integrate or take derivatives or anything like that… I encourage you to use no calculator whatsoever and just estimate… you can write “no calculator” on your exam and I will like it! However, if you feel better about having a calculator, I understand. For full credit, you must put your answer in decimal form, even if you are estimating. That is no fractions, square roots, trig functions, etc. in answer. If you do use a calculator, please find a simple calculator with only trig, square roots and simple math. – Thanks

If you want more practice you can always take more exams. The solutions are on the class websites for these exams.
: Fall 2016 MT#1, MT#1_W16,

Wednesday Midterm #1

Before the exam:

the first part of problem set is complete corrections for MT#1.

This week, we will almost identically repeat what we’ve done the first 4 weeks, but this time for rotational motion.

All the concepts are the same, so taking three weeks, should work well. Your learning objective is to recognize the analogies between the linear concepts and the rotational concepts, and how to use the analogous equations to solve rotational problems.

We will start mixing chapters from OpenStax when I find them appropriate. This will be longer and more technical than my short text notes. I may also write some more chapters, but it is less necessary now that we have finished linear mechanics. It wasn’t appropriate for us to use a standard text before because of the way we introduced all the concepts at once. However, now some of the chapters are appropriate for us because we’ve finished linear motion.

Before Class

  • I posted MT#1 on the main class website. I also posted another copy with some comments and direction. Please start your corrections/talking with friends about these questions.
  • Problem Set #4 posted. Please have a look at it and do the problems as you cover the material.
  • See 4 Lenses of Rotational Motion Oh my, this video is way way too long. Please watch it in two sittings and take notes.
  • Please read our short introduction to rotation, 4.0
  • Please read direction of rotation, 4.1
  • See Circular Motion, Introduction
  • Please read 4.2. rotation connection to linear motion
  • Consider joining Engineers for a Sustainable World (even if you are not an engineer).
  • * I finished grading your midterms and put an improved version of the midterm (with some comments about what students did) on the main class website. We’ll get them back in class today. I was super pleased with how the class did. At the same time, it’s clear that there was not enough time for most students to do the test as they would like to have done. We will talk about how to handle this in class. Please be aware of the 24-hour cool off policy: For 24 hours after you get your exam back, you can not ask me questions about it (and you can’t buy a gun). I want to collect perfect corrections for MT#1 on Tuesday. So, please figure out what you missed yesterday, and what you can learn from it.

During Class
Bicycle Wheel Rotation**