Author: Lee Trampleasure

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PotU 3/16: Learn from Home Weeks 1 & 2

Your assignment for the next two weeks is to read, take notes, and complete questions from Chapter 18, Electromagnetic Waves and Light, in your textbook.

There are five sections in Chapter 18, so your pace should be completing about one section every two days.

When we return to school, you will have an open-notes test on Chapter 18, so be sure to take good notes (printed materials are not allowed on the test, just your hand-written notes as well as your hand-written answers to questions at the back of the chapter.

Learning Resources

  • If you can’t find your textbook, I have scanned it and you can read/download each section here.
  • Starting on Tuesday, I will hold an optional Question and Answer session via Zoom from Noon until 1:00. If you have any questions, feel free to log in and ask.
    • Zoom requires an app for your computer or phone, but the company has a great reputation and is not full of ‘bloatware.’
    • You can visit Zoom on the web here, or using a phone app you can enter this Meeting ID: 569-283-4396
    • I think you need to create a Zoom account to join a meeting but you can use it in the future as well.
    • Due to the COVID1-19 emergency, Zoom is allowing free student and teacher upgraded accounts for the rest of the spring.
  • I will be posting online tools to help with understanding each section, so keep an eye out here if you have questions (I’ll add links below for each section as I create them.
  • You may also post questions on the bottom of each section post, and I will answer them there.
  • If you with to email me, I will answer your email as well as posting the question and answer on the corresponding section page.
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3/13 PotU: Quiz on energy in mousetrap cars and earthquakes.

No warm up today, instead…

image of a sample bubbled in student ID
  • Turn in your bookends/warm up sheet in the tray in the front.
  • Get out your notes from yesterday: One page, handwritten only.
  • Have a pencil or pen, plus a calculator.
  • Clear everything else off your desk.
  • Put all phones and headphones/buds/etc. in your bags.

Quiz

The quiz has 16 multiple choice questions on the front, plus one energy transformation bar graph set on the back.

Remember to bubble in your student ID and read all directions.

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3/12 PotU: Review for quiz

Warm up

Earthquake waves carry energy. Which wave travels faster, S or P waves?

Remember to copy the complete question.

Answer

The P waves get there first (primary), so they travel faster.

Today’s agenda

Today we will conduct a Kahoot!.

You will earn classwork credit for completing it, so include all students names (first and last) when you register. Your username will be randomly created, due to too many inappropriate usernames in the past.

You need to take notes as we go through the Kahoot! You may use your notes from today on the quiz tomorrow.

If you would like to review this Kahoot! later, you can view it here.

Returned quiz answers

Waves and energy quiz answers (Jan 31)

Version A

  1. A
  2. D
  3. A
  4. A
  5. C
  6. A
  7. B
  8. A
  9. A
  10. B
  11. D
  12. C

Version B

  1. A
  2. C
  3. A
  4. A
  5. D
  6. A
  7. B
  8. A
  9. B
  10. D
  11. C
  12. A

Quiz: Earthquakes and Tsunamis, 2/24

  1. .

Weekly quiz: Jan 15

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3/12 AP: Torque!

photo of an old-style beam torque wrench

Equations for torque can be found on yesterday’s page.

Classwork

Complete Problems 1, 3, 5, and 6 on page 253-254.

Intro videos

What is torque?

Sample torque problem

How to use a torque wrench

Homework: Intro to Center of Mass

Watch the following videos on center of mass, and take notes while you do. Your textbook covers this in Sections 8.2 and 8.3.

You will have a one-question quiz tomorrow when you arrive based on the videos below. You can use your notes from the video.

A peak at tomorrow’s video

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3/11 AP: Torque & Rotational Motion

Teeter totters and torque

Image of two different masses at two different positions from the center of a see saw.
Image of a wrench showing forces at different distances from center
To get the same torque, the force at A needs to be greater than the force at B.

Torque

  • Introduction to Torque in your textbook (skim pages 226-230)

Torque is the rotational analog of force. Torque is calculated as the product of the force and the distance from the center.

$latex \vec{\tau }=\vec{r}\cdot \vec{F}$

This is very similar to our $latex \vec{\ W }=\vec{d}\cdot \vec{F}$, to which we needed to add cosine for forces that aren’t in the same direction as the motion: $latex \vec{\ W }=\vec{d}\cdot \vec{F} cos(\theta )$ . We need to do the same for torque, although in this case we need to use sine (since torque is maximum when the force and radius are perpendicular to each other), so we end up with:

$latex \vec{\tau }=\vec{r}\cdot \vec{F}sin(\theta)$

Caution: While the units of Nm, which are the same for work, torque is not energy. It is more similar to force: A net force acting on an object will cause that object to accelerate. A net torque acting on an object will cause that object to undergo rotational acceleration.

Introduction to torque video

With Billy, Bo, and Bobby

Doorknob placement variations

image showing three doors with handles in different locations

Which door provides you with the most torque?

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3/11 PotU: Last day for car trials; breakdown cars.

Warm up

If a car travels 7 meters in 14 seconds, what is its speed? What if it takes 28 seconds to complete the 7 meters.

Show the equations you use with numbers, units, and the correct answer in order to get a stamp!

Answers

  • 7 meters ÷ 14 seconds = 0.5 m/s
  • 7 meters ÷ 28 seconds = 0.25 m/s

Today’s work

Mousetrap car

  • Complete testing your car and calculating the values on the “Page 7” sheet.
  • Make sure you take quality notes explaining what happened as your car moved.
  • Disassemble your car and return:
    • Mousetrap
    • Base wood
    • Wheels (4)
    • Axles (2)
  • When your car is completely disassembled, bring up your parts and your quarter sheet “Group members and what you did” at the same time.
  • Turn in Page 7.

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3/10 AP: Rotational motion, day 2

In class

  • Whiteboard problems from last night’s homework.
  • Start on tonight’s homework: Problems 15, 19, 21, 23 on page 219.

Homework

  • Read Sections 7.2 and 7.3, pages 193-198
  • Solve problems 15, 19, 21, 23 on page 219.
  • If you are up at around 6:30, take a look to the east and look for Mars, Jupiter, and Saturn, which will be lined up right above where the sun will rise.

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3/10 PotU: Mousetrap car testing.

Warm up:

Two parts: Calculate the speed of a car that traveled 2.7 m in 3.5 s. Calculate the average of 3.2m/s, 4.2m/s, and 3.7m/s.

You must have all the information written, show the equation you used, and your answer (must be correct) to get a stamp today. Have your Page 7 of the mouse trap car out as well.

Answers

  • Speed: 2.7 m ÷ 3.5 s = 0.77 m/s
  • Average: (3.2+4.2+3.7) ÷ 3 = 3.7 m/s

Today’s work

Your car should be ready to go. Before the end of the period, you need to:

  • Run your car for three trials.
    • Record the time and distance your car traveled.
    • Record notes describing the motion of your car.
  • Calculate each trial’s speed and averages.
  • Turn in your 1/4 sheet (one per group) describing what each member of your group did. If you had three members of your group, add the third person’s information on the back.
    • Remember, claiming credit for someone else’s work is plagiarism and has negative academic consequences.

Don’t forget Honors photo project, due tomorrow by midnight. TurnItIn instructions are on the web page for the project.

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3/9 AP: Practice with angular speed and acceleration

Friday’s post includes the translational concepts we have studied, as well as the rotational equivalents. If you were absent, be sure to check this page.

Today

  • Read and takes notes on Section 7.1; pages 189-192. Turn in your notes for credit.
  • Work on all odd-numbered problems on page 218-219, numbers 1-13. Show all your work, and show both the SAE (inches, miles, etc.) and metric values when presented with SAE values (OK to use your phone for conversions).
  • Complete all problems for homework.

Remember you can check the answers to the odd-numbered problem in the back of the book, or the scanned versions here.

Videos from Flipping Physics

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3/9 PotU: Running the mousetrap cars!

Warm up

Copy the energy bar graph below, then name the components of your system and add bars representing the energy at the three different stages described.

image showing three energy bar charts plus a system box

Today’s work

Your car should be ready to go; no more than five minutes to get it ready. Before the end of the period, you need to:

  • Run your car for three trials.
    • Record the time and distance your car traveled.
    • Record notes describing the motion of your car.
  • Calculate each trial’s speed and averages.

If your group does not finish these steps, you must come in at lunch or after school today.