# Fall 2016 Mechanics Week 2

Tuesday, first hour: Hand in PS #1, PS#2 questions posted on main class website
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:
1. View Energy Flows
2. View Acceleration Video
3. Do your best to finish the single question in PS#1

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 see the way something should happen?

Tuesday, second hour

### We will measure distance, speed, acceleration, momentum, force, energy, power.

There is an interplay between the concepts of motion, energy, and momentum. We are learning how these relationships are affected by time (rates of change or time derivatives), and forces – how does a force change energy or momentum (how is momentum and energy conserved?).

Before Class:

1.View Forces Effect on p, v, E
2. View Scaling

Thursday first hour:

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.

During Class

Thursday second hour:

We are going to graph some of our own motion next Tuesday. 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.

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 software compatibility. 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. Ian was able to get tracker to work on his Mac only after he transformed 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 how to measure power.
5. Next 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.