# 121 Spring 2018 Week 2

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

Tuesday, First Hour* Announcements ***

1. I posted office hours on the main class website
2. Last Wednesday, I added the scaling video just a little more than 24 hours before class. The policy for the class is that I can change things up to 24 hours before class. A few students didn’t check the website after I posted the video and didn’t catch that video. Subsequently, I’ve been asked to send an announcement if I post something inside of 36 hours before the next class. We will take a vote in class on this.
3. I told the grader to discard the video grades and collect them at the beginning of class time Tuesday, April 10. So, if you can get full credit for all the past videos if you watch them before then. This allows us all to start with a clean slate for the quarter.
4. I’m grading the Big Exam! #1. So far, I’m giving myself a “D-“. I recognize that this is a new format for you guys, and so I’ve rewritten the big exam the way it should have been written with additional guidance and placed it on the main class website and inserted the question into the problem set due Tuesday.
5. I made a minor revision to the syllabus in how you are graded. I moved making a relevant labeled drawing to the first thing necessary in order to achieve a “D”.

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. Finish PS#1 (posted on main class website)
2. View Forces Effect on p, v, E
3. View Pushing Box Problem
4. 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.
5. Read in the textbook
• 2.0 Forces and Work
• 2.1 Power
• 2.2 Units
6. Remember I said I’d look into the finding that people don’t really have different learning styles? Here is what I found.

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

After Class

Tuesday, second hour

We are going to graph some of our own motion, forces, energy, and power tomorrow. I show you how I did it in #3 below. #2 is a super cool way to do it (in my opinion), but some students had difficulty getting the software to work. The full description of the project can be found on a link from the main class website.

Before Class. Please watch the following videos:

1. Please view the video kinematic graphs, LIVE! and watch me draw graphs on a board to represent my motion on a bicycle.
2. View Smarter Every Day Grasshoppers, and try to repeat his experiment with the other grasshopper. You may have an easy time doing this, or you may have great difficulty because of trouble with tracker software (I never got it to work myself). A past student wrote this to help tracker 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
3. I graphed my motion without Tracker. Please view: Graphing running
4. See a video about one way to measure power.
5. Thursday, 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. I’ve never done this in the dark. It might be easier that way if you bring a light to put on you to follow.
6. Readings 2.3 Graphical Analysis of Kinematics
7. Find a description to project #1 on the main class website.

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

Thursday: Meet at Via Carta Today!
we will take data about our movement and then we will analyze it in room 180-272 (NOT in our classroom), because this classroom has access to computers with Lab View on them.

Before Class.

1. I posted PS#2 on the main class website. Please read through it and consider the problems.
2. I posted solutions to PS#1 on the main class website. You should get your problem sets back in class. Please have a look at the solutions with your people and make sure you understand all the concepts involved and how to develop an argument/solution.
3. Graphing a ball toss.
4. Please see how I solved the
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. Would you like a minor in Environmental Studies? It just requires you to take 7 Appropriate Classes, many of which provide GE credit that you need anyway. Please contact your college representative here.

During Class:

Meet at Via Carta by the lowest side of our building and record your video. Bring anything you may need.
So ends the first two weeks of physics class. We will reflect a little about this experience so far.