Free Fall

102 When we investigate free fall, we drop picket fences, and we also fling them upward using rubber bands. This does not work every time, but it is quick enough to get five good trials with usable slopes. We compare the slopes of these graphs to the slopes of graphs made with the dropped picket fences.





96 The data are starting to come in from the video analysis. Not enough yet to tell what the graph will look like. I decided to pull all the data together in a Google Doc.


N2 Lab


75 It is time for the conceptual classes to learn about the relationship between acceleration, force, and mass. We’re doing modified Atwood’s, varying total system mass first. As you can see, we are not a single-vendor school. I don’t even know where those little hanging mass sets come from, but I like them!



IMG_20121219_14145969 Some lovely kinematics graphs in preparation for tomorrow’s assessment.


Applying the Model


67 With some effort, students got through a couple of problems from one of Kelly O’Shea’s packets. There is still a lot of confusion on units, but I am trying to blast through the rest of CAPM this week and planning to start unbalanced forces after break. Wish me luck!

(The rectangular area is obviously not 91 m, but the girl who wrote 16 was on the opposite side of the board from the girl who was writing most of the work. Similarly, the triangular area is not infinity, but 8 m.)





66 Today some conceptual students did their first “practicum.” They timed how long it took the slow-acceleration disk to roll one meter down its ramp. Then they had to determine how fast it had been going when it passed the 1-m mark. While they timed it, I took video. While they debated how to find the answer, I did video analysis. They told me the answer was 0.16 m/s and then Tracker told me the answer was 0.164 m/s. So I told them that they got it right. They were a little stunned, I think, and I hope they were also proud of themselves for doing it. Next step: more complicated questions.


Coming to a stop


64 I skipped yesterday. Today we were working on accelerating situations. The photo was taken of the interactive whiteboard after going over a question. One class totally got it. Another class totally didn’t. One class hasn’t gotten there yet, and half of them have been in “Keystone Exams” yesterday and today, so we’ll have to do some catching up. Maybe tomorrow, when over 200 kids from our school go to the local DECA competition! (December is not a great month for powering through curriculum.)