DAY 11

WARM-UP (10min):

Constant Velocity

Open CH2 of the textbook to Page 38, and look at figure 2-12 in the bottom right corner of the page.

Show your work - don't write the questions

1. What is the position (m) of the runner at Time 0 (zero)?

2. What is the position (m) of the runner at Time 1 (1 sec)?

3. What is the difference in position (m) between those two times?

4. Calculate the velocity of the runner between T(0) and T(1).

5. Repeat steps 1-4 between T(2) and T(6). Find the velocity during that time period.

6. Read the classwork if you finish early

Answer the following for the image below:

7. When and where does runner B pass runner A?

8. Do the two runners start at the same location? If not, describe the difference in starting positions.

CLASSWORK:

1. Goals for You as Students: (5min)

- I want you to leave this class everyday feeling confident, feeling like you are more able to figure out how to solve Physics problems than when you walked in.

- You are all super smart, otherwise you wouldn't make it into this class

- Ownership for learning:

- it's on you, me, and to a lesser extent, your parents, family, and even friends

- Your responsibility: Homework

- Videos and reading are your intro to content

- Your job to absorb as much as you can

- What does it look like to learn on your own from a physics video?

- How do you know that you've learned something?

- Go to the link, and answer the two questions. Put your name at the end of your answer --> LINK

2. HW ReViEw

moving man - last page

3. Lab 2: Velocity and Mass. How does mass affect velocity?: (20min)

- complete data collection for Lab 2

4. A General Procedure for Problem Solving: "GUESSing" (15min)

Once a physicist has used a graph to prove a relationship between two variables, that relationship can then be used to understand all future interactions between those same variables.

For instance, we used a graph of position vs time for an object moving with constant velocity to prove that

v = Δx/Δt. This occurred no matter how fast the object moved. Therefore, we can use this equation for any future situations in which an object is moving with constant velocity.

Consider the following situation. Mr Alexander wants to fly from KVNY (Van Nuys Airport) to KTVL (South Lake Tahoe Airport) for his high school reunion. The reunion is at the airport, and starts at 5:00pm on Saturday. Mr. Alexander's Flight Plan (<-- click the link) shows the distance from Van Nuys to Tahoe. The Cessna 172 that Mr. Alexander rents averages a speed of 115 miles per hour on a clear day with no winds - today the winds are calm and are no factor. At what time should he leave if he wants to reach South Lake Tahoe in time for the reunion?

There is a process we can use when solving math problems like this one called GUESS. GUESS is an acronym that helps organize our problem solving. Here is what it stands for.

Givens: A given is any number written in the problem. Numbers include attached units.

Unknowns: An unknown is the number or numbers that the problem is asking us to calculate.

Equations: An equation is the algebraic representation of the relationship between the variables in the problem. Some problems may require multiple equations to solve.

Substitute: Once the equation has been identified, the givens are substituted in for the variables. Leave the unknown as a variable.

Solve: Use math to isolate all the non variables to one side of the equality and the unknown to the other side.

Let's apply this process to the problem of Mr Alexander's journey to South Lake Tahoe.

G Δx = 289.9mi tf = 5pm v = 115 mi/hr

U departure time - how long the flight takes (Δt)

E

S

HOMEWORK:

#011A: Practice the GUESS procedure on problems 49-51 from page 53 in chapter 2 of the textbook. (10min)

#Goals:

1. Pass the Exam

2. Complete Materials, rough draft of Procedure, trial Data runs

Warm-Up

- none. Write "Test Day".

Classwork

1. Exam

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. 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.

What sources of error did you identify during your experiment?
How many sources of error were sources that your team had control over?
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.

Lab Report

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

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.

What sources of error did you identify during your experiment?
How many sources of error were sources that your team had control over?
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.

What is the relationship between x and t for constant v?
Were you able to achieve constant velocity? How can you tell?

Homework:

1. Watch: https://edpuzzle.com/media/5782b1f927ed9aaf13385304

2. Solve the problem along with Mr. P. If you need to copy, that's okay. This is an introductory example... :-)

3. Answer the four questions

Wednesday, September 9th, 2015

Homework: pg 53 problem 59

WARM-UP: