Blue Sparks

Perhaps some of you who read my post a few weeks ago saw my mention of a large spark my dad created on our trip to Alaska. Well, here's more details.

If you have ever been somewhere dry, you know that static electricity is something to be feared. But on this trip to Alaska, we were staying in a hotel that required walking about twenty meters from our door to the elevator, all the way on carpet. One morning, my dad, being still a young boy at heart, decided to drag his feet along the carpet to see how much static/electrons he could accumulate. By dragging his feet, he accumulated extra electrons, giving himself a net negative charge, increasing with the amount of dragging. Having discovered that the panel on the side of the elevator was grounded, he slowly moved his hand towards the panel. However, he had accumulated so many electrons and potential energy that all of the excess electrons quickly left him for the grounded object, even before he touched it. The large discharge of potential energy, energy converted to kinetic energy for the quickly moving electrons, caused a visible spark coming from my dad's finger, quickly followed by an exclamation of "OUCH!" along with a slight jump. The electrons then probably were transfered to the ground, where they quickly spread out equalizing the charge, effectively canceling it out. Perhaps more electrons moved within the building back to the momentarily positively charged floor, so some electrons going to the ground ended up back in the building. But, like I said, the spark was a bluish color, and very bright. After that, my dad and I discovered that walking while rubbing our hands on the wooden handrail, as well as touching the elevator panel through our jackets, lessened the severity of the shock. I'm glad I don't have to do that on a regular basis. If we ever go back, I wonder if my dad will have learned his lesson, or if the young boy inside of him will prevail again? :-)

P.S. My mom was folding laundry once again (thank you, Mom!), when a sock which was held onto a shirt by static electricity from transfered electrons from the dryer came flying off when she shook it and landed right back in the pile without her noticing it. It was hilarious. :-)

Ions for your hair

Many years ago, my grandpa gave me a hairbrush for Christmas. However, this was not your ordinary hairbrush; this particular one claimed that it used ions to help your hair. It was called the "Ionic Hair Wand Pro," and if I recall correctly, it was supposed to make your hair more managable by causing it to tangle less. (At the time, I was about nine years old and didn't like to brush my hair...at all) Although I'm not sure it helped any, I was contemplating electric forces and charges when I remembered this brush. However, I had never known how it worked, but with my new-found Physics knowledge, I've formed a theory about how it works.

One of the parts of hair that makes it tangle is the outer part, which is make up of little plate-like flakes that can stick out and catch on other hairs' flakes, causing hair to become more tangled. So, my theory is this: the hairbrush sends out ions from a small vent in the middle of the hairbrush that come in close proximity to these flakes as the brush travels through the hair. When these charged particles approach the neutral flakes, they will cause them to become charged either by attracting electrons if the ions are positive, or by repelling electrons if the ion is negative (I'm not sure what the brush sends out). When it does this, the flakes will gain a charge, but they will also create an equal and opposite charge in the middle of the hair either by pulling electrons away from it, creating a positive middle, or by pushing electrons into it, creating a negative charge. Thus, the flakes and middle part of the hair will attract, because opposite charges attract with an equal and opposite force. This will then cause the flakes to lay down flat on the hair, keeping them from sticking up and keeping them from catching on to other hairs, causing the hair to be less tangly. Unfortunately, it didn't seem to work for me; however, that may have been more the fault of my lack of frequent conditioner use and my tendency to always wear my hair down (even in the wind). I wonder if it still works? I should try it out... :-)

Snap, Crackle, Pop!

No I'm not eating rice krispies, although rice krispie treats do sound good right now (although too sugary). Actually, as I was sitting trying to do my homework and watch TV at the same time, my mom was being very nice; she was folding my clean laundry, strait out of the dryer. Although I am very grateful as I know how long that takes, I don't usually pay attention unless I'm helping or I need to monitor the dryer so that my already-too-small-in-the-arms tops don't stay in too long. But as I was drawing polar coordinate graphs, I heard something very familiar: "rackle crackle crackle." I knew immediately what it was: it was my mom unsticking clothes from each other, held together by static electricity. But today, this sound was different, for I had read the assignment on electric charge, and I knew exactly what was going on. When the clothes had been tumbling around in the dryer, the electrons in the outer parts of these items would rub off, being transfered to the objects on which they were rubbing, such as the walls of the dryer, or other clothes. In this case, these two objects built up enough opposite charge to attract each other, since opposites attract. The forces that each exerts on the other are equal and opposite, as well as strong enough to hold them together. When my mom tried to pull them apart, the electrostatic forces fought back, keeping the items clinging together, even to the last clinging fibers which still point directly towards the other object. However, I believe the crackling sound has something to do with returning the charge to equilibrium, but I would have to read more. Oh also, just as a warning: if any of you ever go to some place dry,(my experience is from Alaska) don't drag your feet along the carpet, and don't go touching metal objects that may be touching the ground, because you almost certainly WILL get shocked. You should have seen the spark my dad created(it was blue).

The Thermodynamics of Baking

I love baking. However, I love eating the food even more than the work that goes into its preparation, so combined with my laziness and need to stop eating junk food after the extremely tasty month of December, I don't bake very often. However, last night my dad did that for me; he made a batch of very yummy biscuits (one of which is pictured here) that even though I had just eaten a large dinner and half a cinnabon I immediately dove into. (I need to learn some self control :-) ) But this morning while considering whether to eat another one, as well as pondering thermodynamics in daily life, I thought, "Hey! Biscuts are full of thermodynamics, at least the baking process anyway." When the oven is turned on, the coils producing the heat begin to heat up the air inside the oven by conduction, which then circulates by convection due to the differing densities between the warm and cool air, eventually bringing the entire oven up to temperature. The heat is prevented from escaping by the walls of the oven which, I would guess, are covered with a high specific heat material and/or a material that is designed to reflect the infrared waves from the hot air and heating coils. Then when the biscuits are put in, they begin to heat up by conduction as well. However, the outside will heat up faster, as it has more contact with a larger heat source than the inside does. Then when the outside begins to cook and get hard, it doesn't allow for the expansion of the biscuit anymore as the temperature goes up, turning an isobaric process into an isochoric process. However, that means that as the temperature of the inside rises, the pressure builds. But the outer layer isn't strong enough to contain the pressure, so it splits and releases the pressure, allowing the inner contents to expand once more, just like this biscuit started to do, but the picture's not good enough to see it very well. But sorry, there can be no more pictures of that biscuit to show the split; notice that the biscuit is sitting on a cutting board. It was eaten with strawberry preserves soon after that picture was taken. Yum!

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. :-)