Today we started the AP Physics 2 fluids unit watching this video of a can being crushed as it descends in a lake. Like any paradigm lab, students made observations and enumerated variables that may be related to the crushing of the can. We determined which we could control and measure in the lab, and defined the purpose:
To graphically and mathematically model the relationship between pressure, volume of fluid above, depth below surface of fluid, and type of fluid (density).
We divided these various experiments among the lab groups, and groups started designing their particular experiment.
One group investigated if fluids of different densities result in different pressures at the same depth:
Another group investigated the affect on depth below the surface on the pressure.
Tomorrow, groups will share their qualitative results and then we will focus on refining our procedures to build the model while minimizing uncertainty. I love how students often surprise you in a paradigm lab when they focus on the characteristic that doesn’t affect the dependent variable. I can’t wait for the discussion after the group who measured the pressure in various sized containers with the same volume of water above the probe (which results in different depths for different containers) presents.
This paradigm lab was inspired by the article Pressure Beneath the Surface of a Fluid: Measuring the Correct Depth in The Physics Teacher.