141 Winter 2018 Week 8

Thursday: 2D mechanics (no trig).

We have done linear mechanics in a straight line and rotational mechanics. Now we will introduce components, angles, and trigonometry and spend the last three weeks reviewing the same curriculum with the inclusion of angles. This is a great opportunity to improve conceptual knowledge.

Before class

  • Redo the MT#2 in fine form. The exam is posted on the main website along with some intended to be helpful hints. Please do all 6 problems and the extra questions I added to a few.
  • PS#8 has been posted, please take a look. as soon as possible I may make a few minor changes/additions.
  • Notes for final exam – don’t let your formula sheet get any longer. As we add a few (very few) new formulas, you will want to drop others that are obvious to you now.
  • Watch Intro Video to 2 Dimensions (3.8 minutes)
  • See the video on estimating vector components (1.5 minutes)
  • See the video on 2D Components of Force (8.5 minutes)
  • See 2-D kinematics (3.5 minutes)
  • Watch this famous music video… how did they make that video? I mean, do you love it? You’ve seen it already, right?
  • Read 7.0 in your textbook.
  • Check out PS #7, posted on main class website.

I’m offering a special service to help prepare for the final exam if you didn’t get full credit on a MT#2 question. I will “grade” your corrections for each problem that you want me to in order to make sure you got it right. Please decide which questions you want me to grade. Then you do the problem as if you were handing it in on an exam. After you understand what you did wrong and how to do each problem correctly, please sit down and do the problem with only a formula sheet. Then staple the problems together and submit them to me. You don’t need to include the original MT#2. Next Monday please give me these separately from handing in the problem set. I’ll “grade” them and hand them back Tuesday.

In Class**

  • Review Midterm #2 – Exam Returned
  • Practice Components
  • Hand in project #1 in final form


  • See the video on 2D work (5 minutes)
  • See video on 2D momentum transfer (6.5 minutes)
  • Please read 7.1 in your textbook
  • Finish MT#2 corrections with PS #7
  • Finish PS#7 posted on main class website.
  • Please read PS#8 on main class website.
  • Hey, if you want, check out this video (and the related article) of the latest rocket launched into LEO (lower earth orbit). Remember we calculated the speed necessary to have LEO? What is that in m/s and in km/hr. Watch the speedometer in the upper right as it approaches that speed.

In Class

  • Talk about projects – Project proposal due by next Tuesday.

After Class

Tuesday: we look at how a point mass (radius = 0) can have angular momentum

Before Class

  • Finish corrections for MT#2 and the rest of PS#7.
  • See this video about the mass on the inclined plane (9.5 minutes)
  • Read 7.2
  • Please start on PS#8 on main class website. I’ve updated to the final version at 12:45 PM today, Tuesday.
  • Please do the third 10-question survey to talk about in class.
  • Please consider why the ball on the track still landed back in the car for all angles of incline. You might reflect on what you learned from the inclined plane video.
  • Project #2? In the syllabus, I laid out the second project, where each group makes a video. It’s really a great project and I think students benefit from it, but I’m not feeling it so much this quarter. We have three fewer school days than fall quarter does, and I feel we are more compressed. Also, I don’t feel finished with the first project. In class today, I will ask for a vote to drop this assignment this quarter. I’d rather not spend too much time on it in discussion, so please give the question some consideration before class.

During Class
Components and work.

Wednesday: we look at the conical pendulum
Before Class

  • No office hour today. I apologize for any inconvenience. But please come anyway and work problems together!
  • I posted solutions to MT#2 on the main class website. Please take a look at how some of these were solved.
  • A video on the conical pendulum
  • Read 7.3 on the conical pendulum.
  • Watch Statics
  • There will be no project #2. I indicated during class that it could be optional. However, after some thought, if we’re not doing it as a class then we won’t do it at all. If you were thinking about doing it to raise your grade, I suggest that instead you spend some time working problems with your friends by my office! I hope that’s OK.

During Class
Practice conical pendulum
Practice slack lining?
Get our Project #1 back.


Before Class

In Class

  • Big Exam #6

After Class