## Day 132 – More DI

Physics 11 – More direct instruction today.  Students don’t have to copy out many notes thankfully.  But… yuck, I did not enjoy speaking from the pulpit.  I also included a second worked example:

If you’d like copies of these, here they are:

## Day 128 – Momentum Video Lab

Physics 11 – This is the lab I settled on for conservation of momentum.  Students will use three Direct Measurement videos (dart into cart; Hailey and Connor; Hailey, Connor and Christine) and three videos that they will record themselves of two carts on an air track (head on collision, collision in same direction, collision into a cart at rest).  I thought about giving them an Excel spreadsheet for entering in their data, but that would make the experiment very much a “black box”.  The amount of time this lab is taking is concerning though.

## Day 128 – Collision Analysis

Physics 11 – Students were given two options to analyze and report on a collision.  One option was to analyze two carts exploding apart (spring plunger activated), where one cart has an unknown mass on it. Option two was to analyze the impulse given to a popper toy.

Almost everyone chose the popper. It was the harder one to analyze because students had to incorporate projectile motion in order to complete their analysis.

## Day 122 – Whiteboarding CoM

Physics 11 – Whiteboarding last day’s results was the main even for today but I forgot to take pictures.  By going around the room from whiteboard to whiteboard I posed the question, “what pattern do you see?”  Inevitably the students start to see that in each case, the moment of the objects before the interaction is equal to the momentum of the objects afterwards.  Ah ha! Conservation of Momentum!

I then showed the students how conservation of momentum can also be seen as a consequence from Newton’s Third Law.

## Day 120 – DMV Conservation of Momentum

Physics 11 – Students used a variety of impulse/collision Direct Measurement Videos today. The goal was to collect data and analyze the total momentum of the objects in the video (system).

A couple of groups got a bit confused because there was missing information on the videos (these videos work towards using conservation of momentum to solve for unknowns). I may need to re-jig how I delegate videos to the groups next year.

Overall the DMV are a quasi-reasonable substitution for not having appropriate lab equipment.

## Day 118 – Last Day before Break

Physics 11 – Today the last of my classes got caught up with the momentum activity. Above is an example of student work showing their correct prediction of the force vs time graph, along with calculations for the change in momentum.

Lots of students were missing today which was a shame because we did some really good group whiteboard work on conceptual questions.

## Day 116 – Change in Momentum

Physics 11 – Most of my classes were able to finish their analysis of the colliding cart. I can tell that many of the students are getting really comfortable with moving their concepts and models in and out of different situations, which is really cool.

From their analysis, students reasoned that the “impulse”, or force acting over a period of time, was equal to the change in momentum. We didn’t get into error analysis really, our class time was pretty short today. I might try to have them do another momentum lab to study the conservation of momentum. I do want to have another formal lab report written and graded this time. On the other hand, I am constantly aware of time constraints…