In this interactive introductory physics lab activity students explore the speed of a rotating “pop tube” using two independent techniques.  Video analysis software enables calculation of the tangential speed.  A rotating corrugated tube will draw air from the position of least motion, generating an air flow over the corrugation creating vortices that create audible resonance at specific angular velocities.  Because the rotating tube has different tangential velocities, depending on the point along the tube from the axis of rotation, a range of Doppler shifted frequencies near the central peak can be extracted from an audio spectrum.  The resonance frequencies are collected using a microphone situated in the plane of rotation. The Doppler shifted peak frequency can be analyzed to solve the speed of the moving tube, with the frequency extrema giving towards and away from the microphone.  Lastly, the period of the audio spectrum (point of closest approach to the tube) and radius of the motion provides a third means of estimating the tangential speed.  These results are then compared with those taken by video analysis.  This activity provides students with a practical means of understanding how Doppler shifted waves can be analyzed to find information on relative motion.

In our hands-on lab for calculus-based physics at CSUS, teams of students explore conservation of mechanical energy using PASCO smart carts.  They predict kinetic, potential, and total mechanical energies, then use measurements of position and velocity to calculate and graph conservation of mechanical energy.  Students also roll smart carts down a track and bounce them off their springs observing intervals where mechanical energy is conserved and changes in total mechanical energy due to an external force.  Finally students explore the motion of bouncing balls, using their cart experiments as a model for changes in mechanical energy.  From their observations students develop a framework allowing them to predict when they might expect to see energy conserved.

Traditional introductory physics labs are frequently focused on demonstrating and reinforcing lecture concepts and yet are ineffective at these goals. Often, they are procedural in nature, removing most student autonomy. In a physics course for non-science majors, we transformed our labs from traditional procedural labs to more inquiry-based, skills-oriented labs. This transformation was done using the same lab equipment and only modifying the lab procedures. Students now determine how to create an experimental design, collect data, analyze data, and how to convey findings. The labs provide scaffolding early on, allowing students to develop each of these skills. The scaffolding is slowly faded away throughout the semester such that students must make all of the decisions involved in designing and executing an experiment by the end of the term. We found that this ultimately made students’ attitudes about experimental physics more expert-like. This talk will focus on the theory and design principles for these labs so that high-school and introductory college instructors can see how to integrate experimental decision-making into their labs.