Violining, part two!

Four more days, guys. Just four more days. Hang in there, don't stress, and most importantly, keep up!




With that said, recall from last week how the tensions of both the bow and strings of a violin contribute to its sound. The tuning pegs or the bow's screw need to be adjusted precisely and carefully to produce the optimal sound. Now that the mechanics have been explained (somewhat...), we can move on to the finer aspects of violin: the sound itself!




We've learned in physics that a "repetitive vibration" causes a continuous, periodic, sinusoidal-shaped graph. But if violinists played with a "repetitive vibration," they would be limited to the same note, at the same pitch, with the same frequency. That would be boring! Much more often, we enjoy listening to varied notes, varying (or at least extremely quick) speeds, at different pitches. Here's David Garrett breaking the violin speed record!




There are other aesthetically pleasing things violinists can do to dazzle audiences, too. Vibrato is a vibration in the left hand that causes a pulsating change in pitch. It adds character to sound as opposed to just a flat note. A tremolo is the same concept, except with intentionally a much higher frequency to produce a "trembling" effect. Both take time and skill to develop, but are essential tools to violinists. Without these dramatic variations in frequency and pitch, violinists simply don't sound good, and consequently they wouldn't be successful in getting our money. Most importantly, though, we would lose doc! as one of the people who show up to Orchestra 5 concerts. People like Mozart and Bach and Beethoven would be nobodies. Many violin-makers would lose their jobs. The economy would thus undergo a huge recession. The stock market might explode and the world could end in 2012.


And so I end today with a fun fact: recall that a sound that is ten times as intense is only perceived by humans to be twice as loud. Essentially, a violinist needs to work ten times as hard for you to hear only a two-fold increase in volume. And the reverse must be true too: a violinist needs to work ten times as hard for you to sense a two-fold decrease in volume. Appreciate what we do for you, guys!

The Physics of Violin

The result of a very short weekend and some very substantial writer's block is this week's feature on my very good friend, the violin.

Before reading about harmonic motion and some introductory remarks on sound, it had never occurred to me that music was all about physics. And by next week, we'll know even more about sound. Well then! ....um, I'll cover that next time. Soooooo!

Since sixth grade, when I first picked up a violin, I had messed around with things like tension and friction to get a desirable sound. Granted, I probably used the wrong word there; calling it "desirable" would be extremely misleading. Oh well, as usual, it's Sunday night!

At any concert featuring any string player, the first and foremost requirement is properly tuned strings. A violin's four strings are affixed to four tuning pegs, which when turned clockwise, increases the tension on the string. Consequently, this increases the frequency of the sound produced by the string (the sound's pitch is "higher.") The opposite, of course, results when a violin is tuned counterclockwise. Since so many different tensions can be achieved with the tuning peg, strings can be tuned to whatever note is desired. On the same end, however, tuning is sometimes a difficult and frustrating task. Back when I really was clueless about tuning, I recall breaking a few strings when I increased the tension too much.




Aside from a properly tuned instrument, a violinist's bow must be appropriately groomed with sticky substance, and lots of it. Conventionally, the bow is made with horse hair and coated with rosin. Without rosin to increase the coefficient of friction on the bow, the sound produced is very weak or completely nonexistent. Using too much rosin, of course, results in a very harsh, sticky sound. Another amateur mistake I probably made in sixth grade.






Moreover, the force of tension applies for the bow, too. Turning the screw on the bow (clockwise) increases the tension on the hair. Just like the strings, the hair needs just the right tension to produce the optimal sound. Careful owners of bows always say to loosen the hair completely after playing, each and every time. I say forget it. I generally remember this only after putting my instrument away, zipping it up, and closing the buckle. At which point I refuse to unzip my case, unbuckle my buckle, and take my bow out again, because I just can't be bothered to do all that. How annoying.

And so with a properly tuned instrument, a properly tightened and rosin'd (yes, I make up cool words) bow, a good violinist can start playing and dazzling audiences. Well, not exactly. You can play with an untuned instrument, with an un-tightened bow, without any rosin. You'll survive. I did.

The Buouyancy of Sophistication!

Since ancient times, humanity has sought, nay, required ways to resolve dispute. Ideally, it would be quick, fast, and easy; on these ends, methods such as dueling, arm-wrestling, beauty contests (the judgment of Paris, for you mythologists!) et cetera all failed. This prompted some brilliant individual to recommend the "coin flip."

The ancient Romans believed that "divine will" would express the truly desirable outcome of a flipped coin. Today, flipping a coin is simply a compromise in which both parties have a chance to get what they want. This evolution of methods clearly shows that we, humans, have become sophisticated! No longer is a duel to the death required to resolve a conflict. Now, we can simply flip a coin! Anyone ever thought of doing this for the presidential election? It would save a LOT of money, time, and TV channels.

While planning our recreation time for Thanksgiving, we decided to watch a movie. Our votes were essentially down-the-line divided in half for 2012 or An Education. Since I could not decide right off the bat which movie I preferred, I took out my trusty coin. Unfortunately, sophistication does not guarantee infallibility; in trying to become enlightened of God's will, I ended up flipping it into the cup of water I was drinking.




I noticed immediately that the quarter sank to the bottom of the cup. Of course! Nickel and Copper are both more dense than water; objects will only float if they are less dense than water. Consider cooking oil, which generally has a density of 0.91 g/mL or so (source: http://hypertextbook.com/facts/2000/IngaDorfman.shtml).

The coin I was using consists of 91.67% Copper and 8.33% Nickel (source:http://en.wikipedia.org/wiki/Quarter_(United_States_coin)). Its mass was about 7.5 grams, and its volume was about .625 mL. Thus, the density of a quarter, mass divided by volume, is about 12 g/mL.

The density of water, of course, is 1 g/mL.


Last Wednesday, we ended up seeing 2012. That's right folks. Divine Will indicated that it was the superior, more sophisticated choice.

Good movie I guess, especially the special effects, though the lack of an attractive female lead was really, really noticeable.

Tension with Toreadors; When Things Go Terribly Wrong.

We've encountered several kinds of problems in Physics.

First, we learned that on Earth, one's weight (mass times acceleration due to gravity) is always always always present and always always always straight down. Yet in many of the problems we've tackled, we dealt with objects at rest. That's because when a block rests on a table, a car rests on the ground, or when a croissant rests at the top of the Eiffel Tower, a normal force is exerted on the object--with its vertical component equal in magnitude, opposite in direction to its weight, thus keeping the object at rest.

More recently, in our rotation unit, we were presented with a problem in which the object at rest happened to be a person suspended in the air. Instead of normal force opposing weight, the force equal in magnitude and opposite in direction was friction. I seem to recall failing that quiz, but really, that wasn't my point.

Today I encountered another potential physics problem. One where instead of normal force or friction opposing weight, four tensions do. At rest, the horse is supported in the air by the tensions affixed from the four corners.

Also worth mentioning is that the object is in stable equilibrium. When a force disrupts the horse, it will quickly return back (without any outside help) into a state of zero movement. This is demonstrated in our clip today:





If you're looking for an explanation for the sound effects, I can't say that I understand them either. Sorry.




--------------------------------------------------------------------------------


Somewhere down the line, we will study about electricity. Until then, the random tendency of all the lights in my friend's house to sporadically turn off without any reason or warning remains unexplainable:






This is what happens when things go terribly wrong.


I want my minute and a half of life back.

.... Are you insured?

While I am obligated to keep a level head concerning physics for the rest of the year, the stunning capabilities of physics remain quite disturbing. In many cases, one's fate is in the hands of physics entirely.



The motorcycle driven has two wheels that undergo circular motion, but not necessarily uniform circular motion--the driver in the video made some attempt to decelerate, albeit unsuccessful.

Moreover, the actual collision is very much inelastic. Although Newton's Second Law dictates that an equal and opposite force inflicted on the driver was inflicted on the wall, it certainly doesn't look like it! Similarly, momentum is always supposed to be conserved, yet the driver got significantly slower and the wall did not move either before or after the collision.

That's because in the inelastic collision, kinetic energy is not conserved. But, momentum is ALWAYS conserved. If enough retarded motorcycle drivers opt to experience physics firsthand, eventually the wall will fall over.

Ultimately, the laws of physics can't be changed and haven't been for as long as humans have been in existence. But we do try to protect ourselves, and sometimes, alleviating the consequences is the most we can do. That's why we can save 15% or more on car (motorcycle) insurance by switching to GEICO.



Additionally, does anyone know a good plan for home security or life insurance? I was burglarized today; no witnesses, but the burglar did accidentally leave his cell phone in my house.






.




I want to vomit.

Behind Closed Doors

Breaking News:

We've got some huge developments that are important to mention tonight.


I met Richard's dogs. One of them is big, and white, and fluffy. The other is small, and brown, and kinda fluffy:





This Wednesday is a holiday. For those of you who didn't know, rejoice! After Wednesday, I'll put up a poll concerning whether holidays are better at the beginning or end of the week or scattered on random days in the middle of the week. Honestly, I'd prefer both, I think.






Elephants are not quite as cute as Richard's dogs, but important nonetheless. I think this very well made my whole weekend, which usually doesn't happen on a Sunday night.




Our top story tonight:

Well, after meeting Richard's dogs this weekend, I was feeling adventurous and curious as to just what being a dog felt like. So I experimented. On four legs, instead of two arms and two legs.
What I immediately noticed was that doors were the MOST annoying obstacle to pass through. The problem was that the doorknob requires rather precise turning and rotational movement to operate properly. Not an easy task for us dogs.

But to a physics-literate dog, I could see it all. Doors have a latch to keep a closed door closed. Turning the knob pulls the cylinder in the direction of the turn, and the spring inside this complex system is affixed to the latch and stretched or compressed when the knob is turned. Since this latch is what keeps the door closed, when the knob is turned the latch is adjusted and the door can be opened.


Thinking quickly, I decided that the best course of action was to shapeshift back to human form and proceed from there.
(LIKE A BOSS!)



In other news, my friends thought it would be HILARIOUS to film me, Richard's brother, and Richard's two dogs while we crawled up the stairs at one point. Pictures and clips will be up next week.

Centripetal Acceleration; It's NOT a vibrator.

DANGER:
I WARN YOU RIGHT NOW. Turn OFF your sound before proceeding in this blog. PLEASE, I beg you.




Though it gets a lot of abuse from me in the mornings, my alarm clock is what saves me from absolute tardiness each and every day. I don't know where I would be without it!

Interestingly enough, my alarm clock is one of the ones with a second hand that experiences uniform circular motion. I measured the length of the second hand (the radius of the circle) to be 2.43 cm, or 0.0243m.

The period of a clock is of course, 60 seconds.

Therefore, the velocity of the second hand would be [2pi(0.0243)]/60 or 2.54e^-3 m/s.

Knowing velocity, centripetal acceleration can be calculated as velocity^2/r

(0.00254 m/s)^2/0.0243m

centripetal acceleration = 2.65e^-6 m/s^2.

Not quite what you're used to seeing from textbook problems (and not quite what you're probably used to HEARING, either) ; such small numbers! but cool, nonetheless, right?? especially the purple light???





hao,
I hate you so much.

love,
Andrew