Prior to Spring 2026 I had been setting out 5 stations, each with a sound tube apparatus and a spring or a string apparatus. This allowed students to do the whole lab at one station and avoided rotating among setups and the associated lab notebook issues. Students all worked on either the spring apparatus or the string, but not both because I felt that they were similar enough that there was nothing lost this way.

In Spring 2026 apparatus shortages forced me to return to the format of having 3 sound tubes, 3 vibrating springs and 3 vibrating strings, with students rotating through them. This year students did all three parts, mostly because I dropped the square wave pulse method of measuring the speed of sound using the sound tube. Basically I accepted defeat and acknowledged that finessing this part to make it work was beyond student and TA abilities.

Unlike the 120's and 130's version of the lab, I have students predict the frequencies of the first three modes for the string and spring parts. Then they experimentally determine the frequencies of these modes and compare to the predictions. A significant part of my reason for doing this is because searching for the modes without knowing approximately what frequencies to search around is not easy for me, particularly for the higher orders the amplitude can be small and it is easy to sweep through resonance and miss it.

Since the measurement itself is quick and easy I emphasize the following to the TA's:

• Linear Mass Density. No where in the wiki is this term defined. At this point the students should be able to figure out from the name (and by looking at the dimensions of the other quantities in the wave velocity expressions) that this is the length divided by the mass. i.e. We are training the students not to ask “what does this mean” but instead realize they understand enough to figure it out.
• Uncertainties. All the measurements are straightforward. Groups should be pushed to identify the main source of uncertainty in each measurement and fully propagate uncertainties. They can also be held to a high standard in terms of grading at this point in the academic year.
• In general the TA's should be holding the students to high standards when it comes to things like giving clear and concise descriptions of procedures and interpretations of results. Same for picky things like sig figs, units, plots, etc.

For this part the task is still to measure the speed of sound by moving the plunger and finding the nodes (anti-nodes).

• I do not have anything in this lab that requires plotting, though that would be a reasonable thing to add given how easy the measurements are.