# Day 98: Finding the Velocity of a Toy Popper

In college prep physics, we have been discussing free fall motion. Rather than do a textbook problem, students were challenged to find the launch velocity of a toy popper. They needed to decide what measurements to take and what to do with those measurements. (In an honors class, I might ask students to design 2 independent experiments to find the popper’s velocity.)

It’s amazing (but not surprising) to see students’ “lizard brains” kick in: simply measure time and distance then divide them to get velocity. So we had to have some extended discussion about when that approach is valid.

Equally amazing (and equally unsurprising) was how quickly students forgot the popper is in free fall and thus the slope of the popper’s velocity graph is -10 m/s/s…We *just* did an ILD with a tossed basketball and a motion detector immediately prior to the popper.

We did this once to find the stored energy of the popper. Poppers are a cool little gadget to engage students with.

I keep hoping I can find a magic phrase or reminder to get students to check themselves to see if the lizard brain is at work. So far, I haven’t found it. 😦