# Day 64: Kinetic Energy, Exploding Carts, & Volume

AP Physics 1: Kinetic Energy

I am being compensated by Pivot Interactives as part of their Chemistry Fellows program.

Students used Pivot Interactives to collect data for a relationship between an object’s starting height and its velocity at the bottom of a ramp to work toward a relationship for kinetic energy. Because the activity included directions for how to make each measurement, I got complacent and rushed through the pre-lab discussion, which meant some students were lost on the goal of the activity. I think I would have been better off taking a little more time, and pointing out connections between the directions in the activity and the measurements we discussed. Physics: Exploding Carts

To start working toward momentum conservation, students launched pairs of carts off each other and plotted the ratio of the masses and the ratio of the velocities. Rather than measuring the velocity, we worked out that since the carts have a pretty constant velocity after the explosion, if they hit the end stops simultaneously, the ratio of the distances is the same as the ratio of the velocities. I like that this forces students to start making some predictions about how they need to adjust the distance, rather than waiting until the end to come up with a model. Chemistry Essentials: Volume

The Modeling Instruction chemistry curriculum has a lab I really like to show that 1 cm3 = 1 mL, but I’ve struggled to make it work for my students. Both when I’ve used empty geometric solids and a selection of cylinders, doing the math to calculate the volume in cubic centimeters has been a huge hurdle. Today, I tried the lab using plastic cubes that are 1 cm on each side and it finally went smoothly. Students were actually paying attention to the relationship, rather then getting lost in the math to calculate the solid volume. 