String Bean Physics

This is actually the Physics of string beans, onions, chicken, and their specific sauce from Panda Express. As I let the feeling of freedom from the arrival of Christmas Break, I got dinner with my mom at Panda Express on Saturday night. As I held my three item plate in its bag, I discovered that I couldn't keep the little container holding the string bean chicken from falling over and spilling sauce all over the bag, so I decided to hold it. After a few minutes of holding the rather warm container of food, I thought to myself, "Hey! Physics! Heat!" The small container of food, which was kept hot in its tray was transfering some of this heat to my hand. To start at the beginning of the process: something, probably electricity, heated water in large metal trays, providing the water with heat. This heat is then easily transfered to the metal trays above it, raising its temperature rapidly to a high temperature because metal has a low specific heat, requiring relatively little energy to raise its temperature. This heat is then flows to the food in the metal trays, which was put into a small paper container and given to me. The heat from this food then flowed to my hand, making my hand feel hot. After a while, the food didn't feel so hot anymore. This meant that the system consisting of my hand and the food container was reaching equilibrium, where both the food temperature and my hand's temperature would be the same. However, I'm pretty sure that it didn't, which is a good thing because the food was very hot to begin with, so it probably would have burned my hand, plus the food wouldn't have been very hot anymore :-( . I'm not sure whether this was an isobaric or isochoric process, or neither. I don't think my fingers expanded, but perhaps they did, and I don't think that the pressure inside by fingers increased either, but I don't know. Maybe it did. Scary.....

Physics in Low Brass!

Now, while you might possibly be thinking that low brass instruments usually only serve as metronomes for the rest of the band with very few chances at the melody, that's not entirely true. Although we do find ourselves playing only eighth-notes on down beats more often than the flutes, clarinets, and trumpets do, we often have glory parts of our own (for a good example, listen to "Overture to Colas Breugnon." Go sixteenth-notes!). Or if you want to hear something really different, come to "Merry TubaChristmas," featuring euphoniums(/baritones/me!) and tubas only! I went to a rehearsal for this on Saturday, so along with our awesome lab on Friday, I feel like analyzing the Physics involved in this glorious section of the band.

Now among the various low brass intruments, there are pleny of examples of physics in closed tubes, as our intruments are made of metal tubes and our lips close one end as well as provide sound vibrations. All of these instruments work using the same physics concepts as well. Although the trombone uses a slide instead of valves, as the tuba and baritone do, all three of these instruments legnthen their curly "tube" to create different pitches(however, tuning them to the correct pitches is another story :-) ). Since these instruments are "closed tubes," the harmonics can be calculated using the equation Fn=(2n-1)F1, or (2n-1)(v/2L). For my particular instrument playing the f below middle c, first harmonic present is about 190 Hz, with the other harmonics being twice and three times that. As the valves are pressed, or the slide is lowered, the tube gets longer, increasing L and therefore decreasing the fundamental frequency and all subsequent frequencies, lowering the pitch. But, as we learned in class, these instruments will only let one's lips vibrate at a certain frequency (which explains a lot, especially why I have lots of difficulty "lipping up" my rather flat e flat). When the lip position is tightened to vibrate at the next "open" frequency, the lips vibrate faster, thus resulting in a faster frequency of sound waves and a higher pitch. And over the weekend at TubaChristmas rehersal (an hour and a half of glorious baritone and tuba sound!), I discovered once again that having my lips constantly vibrate at a high frequency is not only difficult to maintain, it hurts! I'm not sure how much it had to do with the frequency and how much had to do with muscle fatigue, but about an hour in I didn't want to play the first part anymore. :-)

Although I'm a devoted baritone player, I have tried trombone as well. Yet in both my attempts to find the correct pitches and listening to our outstanding Band 4 trombonists, I've found that even though the tube of a trombone seems much shorter than the winding ones of a baritone, they have relatively the same sound, as does the small-tubed "valve trombone" I play during Marching Band (except baritones sound prettier. Sorry trombonists, I love my instrument). I wonder if the diameter of the tubes has anything to do with it, because we use the same mouthpieces and our music is interchangable, except for the sound. An interesting question to look into. :-)

By the way, that's me with my baritone in its case and my uncle's trombone, plus the mouthpiece I use for both in my right hand. Isn't my shirt cool? :-)

More Musical Physics!

Talk about a busy musical weekend! Although I know that those in Youth Symphony had it even worse, I had Select Band tryouts early Sunday morning which took at least two and a half hours, and then a Christmas Concert in the evening, plus the Football game on Friday evening (Go Raiders!) and lots of practicing for my tryout. And I didn't realize until a few hours before the concert that I was using Physics with every note I played! Almost every note I play involves at least one of the four valves on my instrument, which consist of a metal rod with holes in it, a metal tube, oil to allow the valve to move, and a spring to return the valve to its unpressed position. When I press the valve, the spring force (-Kx, where x is the distance compressed from the spring's equilibrium point) is equal to the force my finger applies on the top of the valve. Thus the valve has a net force of zero, an acceleration of zero, and in this case a velocity of zero as well since it has reached the bottom of the tube. But when I am not using that valve, the spring force (for I seriously doubt that the spring is ever allowed to reach equilibrium while the valve is in its tube, otherwise the valve may not stay up and play correctly) is equal to the normal force of the valve on the cap keeping it in its tube. This senario is pictured above, with a very bad attempt to draw a spring, even though it was at least my fourth attempt. Since the oil attempts to keep the kinetic friction to a minimum, I wonder what the velocity of the valve is. However, I would need to take a few measurements, such as the greatest and least compression from equilibrium, and experiment to find the force constant of the spring. Perhaps I should do that. It could help answer some questions about why I have difficulty playing fast pieces. But I bet it won't; the instrument is not to blame for my slow fingers. :-)