DAY 13

Warm-Up 

1. What is the symbol for acceleration?

2. Can acceleration be negative, or only positive?

For each of the following P-t diagrams, copy the image into your warm-up. Then...

3. label each diagram as either: positive acceleration, negative acceleration, or constant acceleration.  Assume movement towards the right is positive.

4. Directly underneath each diagram. add a position (dot) diagram, and a motion (vector arrows) diagram.  An example of these is to the left of the projector screen. 

5. How can you tell from a P-t diagram that an objects velocity is changing?

CLASSWORK

• 1. Speed, Average Velocity, Instantaneous Velocity Notes & Discussion

     1.     The goal here is for you to memorize and then translate some information about speed and velocity. By doing so, I hope you'll understand the similarities and differences between instantaneous and average velocity, between speed and velocity, and be able to describe some of those factoids out loud, with confidence. Here we go...

     2.     a. you'll need a notes page in your binder. The title is in bold above

     3.     b. Individually: while skimming, I want you to write down 5 facts, similarities, or differences you've found. Facts could include symbols, equations, definitions, descriptions, etc.

     4.     c. Group: In your group, each person will choose one fact, similarity, or difference, and read it out loud. Don't be super loud. We don't all need to hear you ;-). Listeners should either check the item off on their notes if they have the same bit of info already written down, or add it to their list if they don't. The idea here is that you as a listener have to compare what you have written, and how you interpreted it, to how someone else interpreted it. This helps improve your comprehension. 

     5.     d. Whole class: We will repeat "c" as a class

     6.     e. So, what's the reading??? CH2, pg 43-47

     7. CLASS NOTES:

     8. 1. slope = change in position/change in time

     9. 2. d= vt + di

     10. 3. inst. v is speed and direction of an object at a particular instant

  2. 4. average velocity --> v = (df-di)/(ti-tf)

1. Constant Velocity Problem Solving Review (20min)

   1. lets take a look back, and try two of these problems in class

   2. solve CH2 pg 53 #59 a & b, and pg 54 #60

   3. How do we relate velocity to acceleration in a graph

   4. - Example as a class: pg 61 Prob 1

   5. - for HW, individually practice: pg 61 2, 3, 5

2. #013A: Penny Acceleration Lab Saved for next class

HOMEWORK:

1. Complete all #010A: Lab 2 questions and graphs. These will be checked at the beginning of class, next class period.

2. Next class I will be checking all warm-ups from this year. (Day 1-14)

3. #013A: Is This Acceleration? For each video, list the video title, then answer the question (yes/no) and in a sentence explain Why or Why Not?

a. Ball Rolling Down a Ramp

b. Space shuttle launch

c. Metal cylinder sliding across a table

d. Einstein riding the Graviton

4. #013B: Practice Problems

- Individually practice: pg 61 #2, 3, 5

- Having troubles? Take a look HERE for examples and tutorials and in the book at figures 3-2, 3-4, and especially 3-7. If that doesn't help, drop by at lunch or after school. I usually don't leave until 4:10.

Hurricane Curious?

https://www.youtube.com/watch?v=2Djg4XQVPHw&feature=youtu.be

https://www.youtube.com/watch?v=u7UWWjkpd7o

https://www.youtube.com/watch?v=9Rw1vJBnINg

Need a laugh?

https://www.youtube.com/watch?v=_Uf7x_TYls8

09/13/16

WARM-UP: 

Position v. Time Graphing - Constant Velocity

Open CH2 of the textbook to Page 39, and look at Example Problem 1 in the top right corner of the page. 

Show your work - don't write the questions

1. Answer Question 1 & 2

2. Is the runner running on flat ground, or up a hill? Can you tell?

3. Given constant velocity, what would be the position of runner at t=9.0s?

4. What about t=10.5s?

CLASSWORK:

1. Position v. Time

    HW Review

    Notes and Questions Answered from Flipping Physics:

2. Velocity Inquiry Lab Prep

TITLE: Constant Velocity

Your team will design an experiment to compare the position of an object moving with constant velocity over a series of time intervals.  Discuss with your group the variables that will need to be measured to prove that an object is moving with constant velocity.  Decide which variable being measured will be dependent and which will be independent.  

Measurement Equipment

You will have access to several pieces of lab equipment.  There are ball bearings, ramps, meter sticks, rulers, etc.  You may use objects from home if you like.  Make a list of all the equipment you expect to use.  You are allowed to make changes during the lab.  

Discuss with your group how you could take the proper measurements to prove that your object is moving with constant velocity.  Put together a list of procedures that you will follow.  Perform at least three trials.  

Graphing

After you take your measurements, construct a graph of your data and draw a best fit line. Use Google Sheets via your school Google account, and share your graph with me  Construct one graph for each set of data that you take.  Calculate the slope of the best fit line.  

Percent Error

When you have calculated the slopes, take an average of the three values measured without the phone.  Also take an average of the three values measured with the cell phone.  Now compare the average value with the value that is farthest from the average.  You can calculate your percent error as follows:

percent error = (average - outlier) x 100

                                average

For all scientific experiments we aim for a % error that is less than 5 and preferable less than 1.  The smaller the better.  How did your team do?  Answer the following questions.  

1. What sources of error did you identify during your experiment?  

2. How many sources of error were sources that your team had control over?

3. For each of the sources of error you identified above, suggest a possible way to change the experiment to minimize that source of error.

Lab Report

http://www.chem.ucla.edu/~gchemlab/labnotebook_web.htm

Choose roles: https://docs.google.com/spreadsheets/d/1dGGqrsv05QiIc_LKSh15f-LkLtV4pKCmXYZIih_i7BE/edit?usp=sharing

Introduction

Materials:  List all the materials used in your experiment.  

Procedure:  List all steps that your group followed in this experiment.  Include diagrams of your experimental setup.  Your procedure should be detailed enough that another group could follow your steps and get the same conclusions.

Data:  Data should be listed in data tables.  There should be one data table for each trial.  

Analysis:  Graph your data.  There should be one graph per data table.  Calculate the slope for each graph.  Take a mathematical average for the slopes.  Use the average slope to write an equation that for the line.  Calculate the percent error for your data.  Answer the analysis questions.  

1. What sources of error did you identify during your experiment?  

2. How many sources of error were sources that your team had control over?

3. For each of the sources of error you identified in problem two, suggest a possible way to change the experiment to minimize that source of error. 

Conclusion:  Answer the following conclusion questions.  

1. What is the relationship between x and t for constant v?

2. Were you able to achieve constant velocity? How can you tell?

Homework:

Practice! 19-23 from page 42

Warm-Up.

Think about assumptions you made during your constant velocity experiment. 

A. List at least three assumptions 

(example, the battery is not perfectly round)

B. Choose one of your assumptions, explain it in a sentence, and write what affect it might have had on your results.

(example:  The label has an edge that bumps the ground each time the battery rotates. That impact would increase rolling resistance, and slow the battery down slightly)

Slow Motion Cameras

Slow motion photography helps scientists by giving them more precise time measurements.  It also allows the scientist to replay the observation multiple times.  Watch the following video and notice the details that can be observed when the camera is capable of taking 4000 data points in one second.