LWA Antics

Understanding friction through music

Posted

I go over to my turntable, place a vinyl record on top, then place the needle and hit play. A tempest of thoughts races through my mind about friction.
At Lawrence Woodmere Academy, the laboratory in which I was working deals with the coefficient of friction (COF): the concept that there is a certain relationship to the normal force of the object and the force friction applies to the object. I know I will have a lab report due, but I cannot get the record playing out of my mind. All I can think about is the little stylus gently progressing over the vinyl, and creating sound. “How,” I thought, as the speakers blasted the opening chords of the song, “could scratching create sound?”
At LWA, and I suspect at most other schools, in the science courses, there are both lectures and labs. My lab day arrived. I recall thinking about the record, and involuntarily singing the song “Animals” — a fantastic song, it makes no sense, and the music video is beyond strange, but in the video, there’s a girl playing the guitar.
Violin, I say! I play the violin. The bow moves across a string, which creates a vibration. Wait, the grip of the bow, it’s friction — then it hits me — rosin powder, tree sap that allows the bow to stick to the string. The sound, it depends on the hair and how much rosin is used on the bow.
The bow and the string have a predetermined COF, which could only be influenced by the rosin, not the pressure of the bow. Nothing can affect the relationship of the normal force and friction except an outside medium that is not the force put onto the object — you need a catalyst that changes the coefficient of friction itself. There it is, the answer, in real life.
Then, there I was putting the same record on top of the same turntable. Listening to the same sounds as before, just this time understanding how it all works. I sat down and began the lab report. I felt empowered.