141 Fall 2017 Week 2

Back to Main Class Website

Units: distance (meters), speed (meters/second), or speed is the time derivative of distance: v=dx/dt, Force (Newtons)
Before Class:
1. View “Four Concepts” video, 4 kinds of physics questions
2. View Position and Velocity
3. Watch Veritassium video, Say the Wrong Thing Read more about confusion if you like at NPR: Confusion is How it Feels to Learn
4. Read the paper I published about our learning method in The Physics Teacher. Figure out if this is going to work for you.
5. Read the following in the Textbook

  • 1.1 Momentum
  • 1.2 Energy
  • 1.3 Dynamics
  • 1.4 Kinematics

6. Finish Homework #1
7. Please note that I have posted my office hours on the main class website. Note that I no longer have an office hour on Thursday.

During class:
We look at a collision on an (almost) frictionless surface. Momentum and energy are conserved in a closed system. However, can momentum or energy change forms?
Hand in Homework #1

After Class:
Consider the cart collision today in class:
1) Is momentum conserved? How do you know?… Or don’t you know?
2) Is energy conserved? How do you know?… Or don’t you know?
3) Are there forces and accelerations? Please describe directions and sizes!
4) What about motion? Can you make a speed vs time graph for each cart? Can you make a position vs time graph for each cart?

We are learning to be conscious of the lens (concept) we are looking through or if we are not using a lens. We are practicing using the four different lenses.

Before Class:
0. Please read through PS #2, posted on main class website
1. View Energy Flows
2. View Dropping Rock
3. View Acceleration Video
4. Please read in the Textbook(link on main class website):

  • Energy, please review the energy chapter: 1.2,
  • 1.5 Acceleration
  • 1.6 Potential and Kinetic Energy

In Class:
We will look at things falling and compare times to fall and speed at the end. The goal is to practice using the 4 different concepts and recognize that we are reluctant to use them. Instead of invoking the new tools we are introduced to, we often revert to methods of reasoning that we have used before! The goal is to increase our awareness that we do that!… and start developing new tools. Can we examine our inherent familiarity with how physics works in nature; Can we close our eyes and “see” what will happen?


Before Class:
0. Please identify and do a few questions from PS#2 posted on main class website
1.View Forces Effect on p, v, E
2. View Scaling
3. Elon Musk just uses simple scaling to create disruptive technologies: Quartz Media Story

4. Read about in the text available on main class website:

  • 1.7 Forces, Momentum, Energy
  • 1.8 Applying Lenses of Mechanics
  • 1.9 Scaling – How does behavior change as things get bigger?

During class:
Big Exam #1. In order to prepare for it, please consider this paragraph in the paper I wrote about our learning model:

…students in this class did not start questions with lens identification until after the grading policy was invoked. Even with full knowledge of the rubric and practice in class, the vast majority of the students (and two instructors sitting in on the class) did not identify a lens on the first quiz and thus received a grade of D. Subsequently, most students consistently began answering each question identifying the relevant concepts. It is possible that the change in grading alone would have resulted in students beginning each question with concept identification. Accordingly, a recent publication reports increased student learning with ungraded, timely feed- back and other Formative Assessment techniques.1

  1. J. Haugan, M. Lysebo, P. Lauvas, “Mandatory coursework as- signments can be, and should be eliminated!” Eur. J. of Engin. Educ., 1–14, March 21, 2017; published online at http://dx.doi. org/10.1080/03043797.2017.1301383


Before Class
What if you want to see a video the second time and also want to see the questions? Just click on the small vertical bars at the bottom of the video that indicate where the questions are located in the video.

  1. View Pushing Box Problem.
  2. View this 3 minute video : Energy, Work, and Power. Be prepared to answer this question: a 1000 kg car starts from rest and accelerates to 30 m/s in 5 seconds. Please calculate the average power the car produces to do this. Please put answer in Watts and Horsepower.
  3. Read in the textbook
    • 2.0 Forces and Work
    • 2.1 Power
    • 2.2 Units
  4. On the textbook website, I added a .pdf of all the chapters as a single document… so far, I only have chapters 0-2. You can use it if you want to find a topic, but don’t remember which section it is in.

During Class
Prepare for your activity next Tuesday: You will make a video and calculate the kinematics, energy, momentum to be handed in next Thursday.

After Class
Friday office hours: I won’t be at the 9:00 office hour tomorrow, because I attending Cal Poly’s “Unconscious Bias Workshop”. However, I will start my 11:00 office hour at 10:30 (when the workshop ends.)

Videos I find helpful
Veritasium’s Cool Science Home