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.
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.
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.