38 We were back to school after Hurricane Sandy and it was Halloween! Fun! (Click images for enlargements)



Sandy day 2 The upper left photo is the tree in our backyard that broke, landing on the ground within our yard and damaging nothing. On the upper right, the sign on the door of the Burger King nearby. Lower right is the pole that snapped last night, wiping out power to the homes across the street from us. Lower left is the CVS Pharmacy. When I went for a walk this morning things seemed mostly fine except for the lack of power, closing many businesses like the diner, the nail salon, and the mattress store. The Kohl’s department store planned to open at noon, and Target was open but most of the staff were busy taking refrigerated and frozen items off the shelves for disposal, since they had lost and regained power. The Chik-Fil-A was open, too, as was the LA Fitness (they are on the same block as the Target). Sometime this afternoon I will find out if I have school tomorrow. I am hoping yes.



Hurricane Day 1

Sandy day 1 We were off school today for Hurricane Sandy. This view is from the window of my office.

We probably would have been just fine being at school, but I think it makes a lot of people happier not to have to worry, especially having emergency responders and parents not having to worry about teenage drivers on the wet and windy roads. The winds are supposed to pick up dramatically tonight, so I don’t know if I will have power tomorrow. Anyway, with public transit shut down, my husband also stayed home today. We’ve managed to keep busy and dry!

Demo Day

The day after 37 Oops, didn’t post yesterday. Nothing exciting to post on, it was more practice with system schema and FBDs and the last class finally did the spring force lab.

Today, Saturday, I spent a good chunk of my day at our local physics teacher group’s Demo Day. We are the Southeastern Pennsylvania Section of the American Association of Physics Teachers (SEPS AAPT), and every fall we get together and share cool stuff that we do. I showed off the Desmos online graphing calculator, because it is cool, and I demonstrated wave superposition using addition of sine functions. There was a wide variety of stuff, from a 3000 F capacitor (2.7 V max) to the index of refraction of “candy glass” to collecting liquid oxygen between two magnets with the help of liquid nitrogen. At the end, Ken Fink of Wondergy showed off his magic trick, framing it as a center-of-mass demonstration. The woman’s center of mass is over the chair, so she is supported by it. (It is even more dramatic when Ken takes the board out from under her.) A lot of teachers showed up, and a good time was had by all!


36 The conceptual classes are slowly working through a version of Kelly O’Shea’s packet for Balanced Forces. They were doing a decent job of the system schema diagrams and FBDs. Students were working on this in class in small groups, and each group made a whiteboard of the same material, and we compared them and looked for differences. We then discussed whether those differences were acceptable or if they made the solution incorrect.





Meet #1 Scores


I debated putting this post up, but I decided that if I am truly documenting my year I should include some of the extra time I put in. So last Saturday, I (and my colleague) spent 7:30 AM to 12:30 PM chaperoning 19 students at a Physics Olympics meet at a nearby high school.  For weeks we’ve been taking turns staying after school with the kids as they prepared for the meet, and Saturday was the first of our three competitions (the next is in December, and the last will be in February). In addition to chaperoning, I ran one of the events (the coaches at the various schools take turns writing the rules for and running the various events). I was thrilled that our team came in 3rd overall at this meet, considering that we usually hover in the 7th to 9th place range. I hope my team can maintain its current advantage and it would be awesome if we could make it to first or second place!

The teams currently in 1st and 2nd place dominate the competition, and will be hard to beat. Penncrest has taken home the banner (literally – we have a banner that goes to the winner’s school until the next meet) more times than I can count.


Spring Force

35 Today a couple of classes were determining how much force it takes to stretch a spring different lengths. Before this year, I always did this lab in the energy unit, but I’m following Kelly O’Shea’s lead and doing it in the Balanced Forces unit. It’s a force, we are investigating it. We already investigated the gravity force.



Potential Energy

34 In AP Physics we are starting potential energy curves. I love these because of the connection to quantum mechanics, and because when I was in college taking quantum mechanics I totally didn’t get it. I could look at the classical curve for an oscillating particle and calculate the quantized energy levels, but I don’t recall understanding the connection to classical potential wells. In addition, for a long time I confused the gravity potential well with the curved shape of spacetime due to a massive object. They are NOT the same thing, and not the same mathematical shape! It is amazing how much you learn when you teach.

More Hover Puck


33 Today we played with the hover pucks some more, this time with the help of some skinny rubber bands tied together. We discovered that if two rubber bands were pulling equally in opposite directions and one let go, the puck would go towards the one that didn’t let go. We also discovered that if you try to use the rubber bands to LIFT the puck, they stretch really really far…much farther than they stretched when we were pulling the rubber bands horizontally or at an angle.  Additionally, if you pull a hover puck with one rubber band and expect it to go at constant velocity, the rubber band will go slack as you try to maintain constant velocity.

By the way, in this photo the puck is not turned on, so it is at rest on the floor. A student is pulling with a rubber band but not enough to make the puck start moving.



Hover Puck

32 Today we all sat on the floor and played with the hover puck. Each class made observations, and we talked about interactions. Today was the first time students saw an interaction diagram. It was a first for me, too. I have never used them. I think they started being used after I took Modeling Instruction workshops in 1997-98. Anyway, the students seemed to think it makes sense as written.

I praised the student who said it sounds like there is a fan inside the puck, since we could not see the fan so it is not a direct observations. We also checked whether the puck could be said to “float” by sliding paper underneath. One class wanted to send the puck all the way down the hallway, so we did that.