# Day 11: Wrapping up the Non-linear Labs with a Musical Challenge

Today in Advanced, we walked through a quick WB discussion of the pendulum experiment.  The students saw that the only factor the affected the period of the pendulum was the length. With eight groups, we had 4 different masses, with two groups doing the same mass. The students saw that regardless of the mass, the slope of the linear period squared vs. length graph was fairly constant.  We did not delve into what the constant(s) was at this point.  I explained, that as we did with our last experiment, we are going to complete a challenge.  The challenge this time was to create a pendulum that would keep time to a song playing in the background.  I learned about this awesome challenge from John Burke a few years back, here.  (although I think he credits Frank Noschese).  The students get no equipment, only the Logger Pro graphs and the EOL they developed.  As explained in Burke’s post, an on-line beat frequency website can be used to determine the beat frequency of the song the student group chooses.  I REALLY like this challenge . It allows some choice for the students, brings in some unit conversions and the relationship between period and frequency.  After the students predict the necessary length, each group (in turn) sets up the pendulum, we crank up the song and let it go.  We check the actual frequency using a Vernier Photogate with pendulum timing.  Here is a sample I made for the students.  Tomorrow after the Graphing assessment, we will check the challenge!

As explained yesterday, the General students worked on using Logger Pro to create linear graphs for three data sets we provided them.  They started the hour off with a quick WB of the Mass on a Spring experiment. They were able to see that the spring DOES have an effect.  Like with the Advanced group we did not worry about the exact meaning of the slope, just used it to show that the spring mattered, just like the inertia balance did.  I have to remind myself, that as long as I circulate around the room answering questions and pointing things out, the students work very hard.  Tomorrow they will be introduced to the same type of musical challenge…  determine how much mass will be needed to get their spring/mass system to keep the beat to a song in the background.