*AP Physics C:* I had to leave early today, so AP Physics students practiced their rotational motion problem solving using this direct measurement video. Click picture above to view video (QuickTime).

Here’s the lab handout. (It is focused on rotational kinematics and energy because we haven’t done torque and Newton’s Second Law for Rotation yet.): LAB DMV Bike Wheel Energy 2015 (word)

*NGSS Science and Engineering Practices:
#4. Analyzing and interpreting data
#5. Using mathematics and computational thinking
*

]]>

What’s true about the forces in the constant speed cases? In the speeding up and slowing down cases?

Then I tried to address the misconception/difficulties kids have with constant speed = balanced forces (wouldn’t it just not move?) by demo’ing dueling fan carts. First with fan carts off, then with both on — what happens after I push?

*NGSS Science and Engineering Practices:
#2. Developing and using models
*

]]>

#1 Because we haven’t seen the rotational kinetic energy formula yet, they had to determine the linear speed of each sphere first for this problem:

#2. This one is easy.

#3. For this one, they had to figure out the *net* velocity of each sphere. The orange ones were easy. The blue ones were trickier (2D vectors!).

And low and behold … all that crazy work to work out #3 turned out to yield the sum of #1 and #2!

*NGSS Science and Engineering Practices
#5. Using mathematics and computational thinking*

]]>

*College-Prep Physics:* Students presented their mini-posters to each other today. Although they worked in groups of three, I wanted each student to present their poster. So each person in a groups was assigned a number (1, 2, or 3). All the 1s presented to each other, all the 2s presented to each other, and all the 3s presented to each other. The students who were listening had a feedback rubric to fill out. To save paper, I turned the rubric into a Google Form and had students use iPads to complete a form for each poster presentation. Each student had 4 minutes 45 seconds to present, and then 15 seconds to move to the next poster. I used OnlineBoxingTimer.com to set up each “Round” and “Rest” time and projected it. (Last year I used the iPad app Circle Timer, but I like that this boxing timer is web-based.)

*NGSS Science and Engineering Practices:
#8. Obtaining, evaluating, and communicating information*

]]>

*College-Prep Physics:* Students worked on making their scientific mini-posters for their pull-back toy truck lab.

*NGSS Science and Engineering Practices:
#8. Obtaining, evaluating, and communicating information*

]]>

*College-Prep Physics:* Today students designed their own labs using pull-back toy trucks. They formulated their own question, designed their own procedures, collected data, and analyzed it. The one stipulation was that both the independent and dependent variable must be quantifiable because they are developing a specific mathematical model for their data. Later they will be presenting their results on mini-posters and sharing with the class.

*NGSS Science and Engineering Practices:
#1. Asking questions and defining problems
#2. Developing and using models
#3. Planning and carrying out investigations
#4. Analyzing and interpreting data
#5. Using mathematics and computational thinking
*

]]>

*Astronomy:* We’ve been using the activity-based text “Investigating Astronomy” for our semester-long astronomy elective. Each unit ends with a project. For the Earth-Moon-Sun System unit, the project is to make a calendar, with each month about a particular Earth-Sun-Moon phenomena. I decided to spice it up a bit by having kids assume the role of an Educational Outreach and Social Media manager for an astronomical organization. They had to choose a social media platform (Twitter, Facebook, Vine, YouTube, etc.) and create 8 tweets/posts/vines/videos etc, one for each specific phenomena. They were not allowed to copy/paste pictures off the internet. They had to draw their own pictures or model the phenomena in a photograph. The results were due today and some were pretty cool. Some groups made fake tweets (see picture). One group was inspired by Veritasium and made their own “interview” videos (I can’t share the video online because I don’t have permission of everyone interviewed in video). Here’s the project details:

**Unit Challenge: Astronomy Social Media**

- What is the scale of the E-S-M system?
- How does the sun rotate?
- How does the moon rotate?
- What causes the moon phases?
- What causes a solar eclipse?
- What causes a lunar eclipse?
- How does Earth go through phases?
- What was the importance of the lunar cycle in ancient cultures?

- Each post/tweet/etc. must have a model to illustrate the concept.
- This model may be photos of a physical model (preferred) or a diagram you create.
**You may NOT copy/paste images directly from the internet, books, etc.**

*NGSS Science and Engineering Practices
#8. Obtaining, evaluating, and communicating information
*

]]>

*College-Prep Physics:* Today was our “Buffet Quiz” — one last chance to demonstrate mastery on this quarter’s standards. Check out this student’s improvement!

]]>

*AP Physics C*: Predict the landing point of a ball rolling down and off of an elevated incline. (Note: We haven’t studied rotational energy yet. So their prediction will be further than the actual landing point. That’s part of my plan to motivate our study of rotation.)

One group got resourceful and starting looking for help online. I thought my trick was going to be ruined, but when they did their calculations, they ignored the rotational energy term that was in the graphic they found. *whew*

After taking measurements and grinding through their calculations, they put their target on the floor and held their breath as the ball rolled down and off the ramp.

Yep. They were off by about half a length of paper.

“What’s going on? Were we supposed to account for friction? Air resistance? Did the mass actually matter?”

So I rolled a few other things off the ramp. The first being 3 steel balls of different sizes (front row in picture below).

And the all landed in exactly the same spot as the original ball. It was really amazing.

Then I rolled one of the hollow metal balls (back row, center). And it landed shorter.

“Wait, let me try that again.”

Still short. Then I rolled the hollow yellow ball and the ring. Both short.

“Hmm.”

Then I rolled the black disk. That landed between the other landing points.

Now everyone is thoroughly perplexed. I love rotation!

*NGSS Science and Engineering Practices
#5. Using mathematics and computational thinking *

]]>

*College-Prep Physics: *We discussed the results from Wednesday’s friction lab:

What does the slope mean? How does the slope relate to the “grippiness” of the two surfaces?

Then we repeated the experiment with our shoes to determine the “grip factor” between our shoes and the tile. Then used the grip factor to extrapolate to how much friction there would be when we’re wearing our shoes.

Theoretically, the tug-of-war team that wins is the team with the most friction. So we used the friction calculations of the students who wanted to participate in the tug of war to determine the winning team.

Time to test our prediction!

##BFPM

*NGSS Science and Engineering Practices:
#2. Developing and Using Models
#4. Analyzing and interpreting data
#5. Using mathematics and computational thinking
*

]]>