Blog 13

In places such as Las Vegas, light shows are extremely common.  However, as we learned in the video that Mrs. Provencio showed us, water shows such as the ones at the Belagio are very special.  The spouts of light that are shot up from the water cannons are also illuminated with lights, however, the light only appears within the tube of water, and not in any other surface.  After this chapter in physics, I discovered that this is possible due to the principles of total internal reflection.  The refractive index of air is lower that that of water, therefore, when the light is shot through the tube of water, the light continuously reflects through the length of the water, not exiting the tube of water at all.

Blog 12: Physics and Music

From 7th to 9th grade, I participated in band at 'Iolani.  I played the clarinet, and one question that always puzzled me was, "Why does my instrument sound so much lower than the flute when they look very similar?"  After these past few weeks in physics, I have finally learned the answer to that question.  It is not a matter of the material of the instruments, although that does make a slight difference, but rather on how we (the musician play each instrument.  While playing a clarinet, we cover one end of the cylindrical, tubular intrument, making it a closed end tube.  The flute is played by blowing air across an opening, but not covering the opening entirely, therefore it is an open ended tube.  In a closed ended tube such as a clarinet, the sound waves travel twice as far as they would in an open ended tube like a flute.  This larger distance therefore makes the frequency of the sound in the clarinet less, which then makes the sound from the clarinet sound much lower than the flute.

blog 11: induced voltage and current

A voltage can be induced on a loop or coil of wire if it experiences a changing magnetic field, therefore a changing flux, which causes the loop to have its own magnetic field, therefore its own current.  In other words, if a permanent magnet is moved in and out of a coil of wire, the changing magnetic field from the permanent magnet will induced a voltage and therefore a current in the coil of wire.  Inducing current this way can be an extremely useful way of creating energy and electricity, when an outlet or batteries are not available.  In many flashlights today, you are able to either shake them or turn a crank on them, which in result produces a light.  These flashlights are utilizing induced current from a permanent magnet that moves in and out of a coil of wire when you apply mechanical energy, such as shaking or cranking.  Some of these types of flashlights are also able to store some of the electricity that is produced from the induced current in a capacitor, which is extremely useful in situations where an alternative source of power is not available.
 

Blog 10: Electric Circuits

I was watching ESPN recently, and a commercial for a NASCAR race came on.  Although I had believed that the "sport" of NASCAR was simply left turns (which it technically is), I realized that it could be a very good analogy to an electric circuit.  Some car races are even called "circuits", so it made it even easier to connect it to an electric circuit.  The car represents the electron, and the person inside the car represents the energy.  The race track represents the wire, and the cars (electrons) travel along the "wire".  The resistance on the "wire" is the friction that wears the tires down, and also the width of the track.  When the track is slimmer, the cars cannot pass through that section of the circuit as easily.  The "battery" in this scenario would be the pit crew.  Because the pit crew makes repairs to worn down cars and replaces tires, it acts like a battery which gives the electrons more energy in order to continue to move along the circuit.  There is not really an "energy user" in this analogy, therefore a NASCAR race would be more like a short circuit, because there is not a significant amount of resistance.

Blog 9: Electric Fields

I remember that when I was a young lad in elementary school, there was something that made me a feel a bit uneasy when I climbed onto the playground.  Occasionally, when I would run merrily around in the playground, my hand would feel a sharp sting when I touched one of the metal bars of the playground frame.  For a while, I had believed that it was due to the sun heating up the metal to unbearable temperatures until it became so hot that it would burn your finger if you touched it.  However, as I matured and as my mental intellect skyrocketted, I discovered that it is actually caused by the phenomenon of static electricity and the transfer of electrons.  If our body becomes negatively charged due to static electricity, we have an excess of negatively charged electrons, and our body wants to give those extra electrons up.  When we make contact with a electrical conductor such as a metal playground bar, the excess electrons rush to the less negative bars out of our body.  The transfer of electrons from our finger touching the bar causes a shock.  Our body can become negatively charged through a number of ways, the most common being friction.  I believe that when I would slide down the slide, the friction between my pants and the slide transfered electrons from the slide to my body, giving me a negative charge.
 

Blog 8: Moment of Inertia

When I was playing mustang baseball, one thing that I had always used to do was to try and balance a baseball bat on the tip of my finger.  Initially I had thought it would be extremely difficult to do, but surprisingly, it was extremely easy.  For a while after that, I had always believed that it was easy for me to do simply because I was very talented at it.  However, when I saw that many other people could do it, I began to wonder why it was so easy, until this year in physics.  The mass of the baseball bat is distributed such that most of the mass is at the top half of the bat, while the bottem half of the bat (the handle) is extremely light.  I learned that because of this distribution of mass, the moment of inertia of the bat is very high, meaning that it is very hard for the bat to begin to rotate.  Because of the high moment of inertia due to the majority of the mass being far away from the point of rotation, the end of the handle of the bat, the bat is extremely easy to balance on a person's finger if they balance it on the handle side.

Blog 7: Centripetal Force

I remember playing a racing game in Jungle Fun at Ala Moana and after the most recent chapter, I realized that it had to do with physics! In the game, you would be driving a Ferrari, trying to go as fast as possible and to beat whoever you are racing, in my case it was Troy. Of course I destroyed Troy in the game because I'm super fast, but only now I realized that the game had some principles of physics in it. In the game, there were many sharp, round turns. These turns were sharp because the radius of the circular motion was relatively small. When making the turn, I would have to slow down or else I would go off the road and flip over. This is where I realized that there is physics. We have to slow down in order to reduce the velocity of our Ferrari because the radius of the circular motion was so small. Because the radius was so small, the centripetal force that was required to keep the Ferrari moving in the tight circular motion was very high. In order to keep the centripetal force requirement low enough for the centripetal force, friction, to keep the Ferrari moving in the circular motion. When the velocity was too high, the centripetal force of friction was not enough to keep the Ferrari moving in a circular motion because a higher velocity increases the requirment of the centripetal force. Because the velocity was too high, the car would either go off the road and crash into the wall, or flip over entirely.http://img.slidetoplay.com/screenshots/Ferrari_GT_007.PNG