The decals were installed on the trailer for Huskie Robotics, FIRST Team 3061 earlier this week. Several of the students worked to replace the jack that we broke and install a new spare tire holder. We also now have a dolly with which to maneuver the trailer so we won’t break the jack again. I’m reminded how awesome the trailer looks every time I pull into the parking lot!
We are now getting to the challenging problems where students apply the unbalanced-forces particle model to problems involving multiple objects and friction in unexpected ways. Here is one of my favorite problems:
The diagram below shows a large cube of mass 25 kg being accelerated across a friction- less level floor by a horizontal force, F. A small cube of mass 4.0 kg is in contact with the front surface of the cube. The coefficient of static friction between the cubes is 0.71. What is the minimum value of such that the small cube will not slide down the large cube’s side?
Here is one group’s whiteboard solution:
I wanted to change the dynamics of students working on in-class practice programming activities. I had forgotten that also wanted to introduce pair programming at some point this semester. Now is a good time! I’m not an Extreme Programming zealot, but I am a proponent of Agile Software methodologies and believe pair programming can be quite valuable. We started watching this video to introduce the main concepts. I’m hoping that pair programming helps keep students more on tasks, the class move at a more similar pace, and struggling students better understand the concepts.
Here they are:
Problems involving someone in an elevator are some of my favorite problems to Whiteboard. It leads to a great discussion of the difference of the force of gravity and how heavy we “feel.” Riding in an elevator and feeling “heavy” or “light” is something that all students can relate to and then connect to the normal force of the elevator floor on the person. Often students have extraneous forces on their free-body diagram (usually the cable supporting the elevator). However, this group drew a great system schema that clearly showed the the cable was not interacting with the person and outside of the system.
I have a couple of students in my AP Physics B class that love to prepare an extra whiteboard with a visual pun related to our current topics of discussion. After we discuss the whiteboards for the various problems, they present their extra whiteboard and we laugh (or groan). Yesterday, we watched Smarter Every Day’s Prince Rupert Drop video (one of my all time favorites) since we are studying thermodynamics and have already studies stresses. Here was the visual pun for today: