# 141 Fall 2018 Week 2

Back to Main Class Website

Monday:
We are going to graph some of our own motion, forces, energy, and power tomorrow. In these videos, you will see several ways to extract kinematic data from a video. The full description of the project can be found on a link from the main class website.

Before Class:

1. Please view the video kinematic graphs, LIVE! and watch me draw graphs on a board to represent my motion on a bicycle.
2. Do this short survey #1 – it counts as a video. Please consider your lens all the time.
3. View Smarter Every Day Grasshoppers, and try to repeat his experiment with the other grasshopper. You can download Tracker at this website. You may have an easy time doing this, or you may have great difficulty because of software compatibility. A past student wrote this to help: Tracker Video Instructions. Please work together. In the face of fighting with malicious software, you need good friends. All the same, if it doesn’t work for you, please do your best to estimate the acceleration using my Excel method in the graphing video I did below. One student was able to get tracker to work on a Mac only after transforming the video into a .mov… here it is Grasshopper .mov
4. Finish PS#2 to be handed in during class.
5. You will likely use Logger Pro to analyze your motion data, so please see how we can collect our kinematic data using Logger Pro.
6. Please see how we can analyze our kinematic information from Logger Pro using Excel.
7. Tomorrow, Tuesday, we’re going to meet at Via Carta to take videos of us to calculate kinematics, forces, energy, power, and look at momentum conservation. The first project description link is on the main class webpage. Please take a look at it. You can actually do this analysis without any software (Logger Pro or Tracker). I show you how to do this in the videos for tomorrow. You can look at them today if you want.
8. Readings: 2.3 Graphical Analysis of Kinematics
9. See solutions to Big Exam #1 on main class website.
10. HEY, Refresh the main class website – this is necessary in order to see the newly-posted resources.
11. Read the description to project #1 on the main class website.

During Class
Warm up problems,
Practice and prepare for activity tomorrow.

Tuesday: Meet at Via Carta Today!
The vector sum of the Forces = mass * acceleration.
we will analyze data on our movement.

Before Class

1. Wow, Thanks to Ryan and Sara, I was able to download Tracker from this website and use it! This is great for us because it means we don’t need to use university computers. Please try to do it yourself on your computers before tomorrow. The instructions from yesterday and Smarter Everyday Video can also help.
2. I graphed my motion without Tracker. Please view: Graphing running
3. Graphing a ball toss.
4. Please see how I solved the
5. PS#3 is posted. Please read through it before class to see what’s coming.
6. I was wrong about office hours yesterday. Monday office hours are at 4:00, not 1:00. So, anyway, we had a good time after class. But next Monday, we’re revert to 4:10 office hours.

During Class:
Meet at Via Carta by the lowest side of our building and record your video. Bring anything you may need. After you take your measurements, we can go to 180-272 and 180-273.

Wednesday:Vectors in the four lenses, proving energy formulas.

1. I’ve changed office hours to every day after class, 10:00 AM, as well as 9-11 Friday.

We will explore more complicated dynamics problems.

Before Class

• Two videos describing the role of vectors: Vectors: Forces, momentum, and Vectors: Energy and Kinematics
• See a video about how to measure power.
• Get the flu vaccine! Last winter, more than 80,000 people died from the flu. College students are the group that is least likely to get the vaccine, but they suffer significantly from getting the flu. Please read about it if you like.
• See video on
• Also, see the video about Doc Edgerton’s Photograph of Denny Shute hitting the golf ball
• Read section 2.4 (Vectors and Direction)
• Complete your project from Tuesday. Come to class with questions.

During Class

• So ends two weeks of 141. How is your experience so far?
• Work on your project. Finish it up!

Thursday: Dynamics Protocol

Wednesday in class, we talked about the problem of pushing a car, using the energy lens. To clarify, energy and the work I do is a scalar. Work can be positive or negative… but it doesn’t have a direction. The displacement and force are vectors. When the work decreases energy, it’s negative work.

Before Class

1. The Elevator Dynamics Problem
2. Please see this video demonstrating the dynamics protocol.
3. Bozeman Science FBDs
5. Please do this short Survey #2
6. Please see your feedback to me from yesterday’s class. It’s posted on the main class website.

Then what is equilibrium? How do we find the resultant force? We introduce the “dynamics protocol” (Big Exam on this today)

During Class

• Big Exam #3 Be ready to demonstrate perfect dynamics protocol.
• How do you keep the water in the bottom of the bucket?
• Hand in project #1?
• A string breaks
Would you like to have a garden, or learn about aquaponics, growing mushrooms? Bee keeping? Tree nursery? Please consider coming to the
Student Experimental Farm this Sunday at noon, or thereabouts. How do I get to the SEF?

Optional video: Veritasium on how they measured gravity waves