This year, we tried a new lab practicum for the constant-acceleration particle model unit. I don’t think we came up with on our own, but I don’t remember where I saw it. Students are presented with a constant-velocity buggy, a ramp, and a marble. They have to mathematically and graphically model the motion of the buggy and marble as it rolls down the ramp. After they have created their models, I provide them with a displacement for the buggy perpendicular to the end of the ramp. They then calculate from where to release the marble such that it rolls into the seat of the buggy.
Based on my observations of my class today as they worked on the lab, I was very surprised when most groups missed the buggy entirely. Only after checking over their calculations after school did I realize that most groups made the same mistake. They incorrectly interpreted the slope of their linearized position vs. time squared graph as the acceleration of the marble when, in fact, the slope is one-half the acceleration of the marble. They then used this incorrect value of the acceleration to calculate the initial displacement of the marble.
We now have something to discuss tomorrow.
##capm ##practicumlab ##setbacks