jrosenberg5

Jordan Rosenberg's Wikilog Period 6 CP Physics - Mrs. Burns - 2011 toc

Chapter 5 - Section 1
There are two kids that created there own instrument with a weight pulling a string tight with a can in the middle, this is a guitar like instrument. It seems very loud.
 * __What Do You See?__**

Today, guitarists change the sound by holding the string that they are playing tighter at different positions on the neck of the guitar, known as frets. The closer the fret is to the body of the guitar the higher it is. There are 6 strings each with different thicknesses, the thicker the string the deeper the sound. In order to play the highest sound you'd use the thinnest string and hold it at the fret closest to the body of the guitar.
 * __What Do You Think?__**

__** Physics Talk **__ To produce a pitch you need a vibration. A pitch is how high or low the tone is.The pitch goes up when the tension increases and/or when the length of a string decreases. If you increase the tension and the length of the string the pitch goes up a lot. That's how instruments are played; the player tightens the tension or shortens the string with their fingers to make a different pitched note come out. Vibrating surfaces act in the same way because they also move like waves.

__** Checking Up **__ 1.) When tension is increased the pitch goes up. 2.) When you decrease the length of a string you increase the pitch. 3.) It increased tension, therefore increasing the pitch. 4.) When you hit a percussion instrument it acts like a string because it has waves that are very similar to that of the sound waves of a string.

Pitch increases when tension increases and when the length of the string decreases. The motion of the string when "plucked" looks like the graph of a sine function. (The "origin" of the graph is called the equilibrium position of the string. The highest point is called the crest, which is the position of maximum amplitude, the lowest point is the trough, which is the position of minimum amplitude). The wave travels down a medium. The medium is the substance that carries the wave. The amplitude is from either the crest or the trough to the "origin" or x-axis that it is based off of. The length of one wave (one sine period) is the wavelength. The symbol for wavelength is lambda. This is from one position on a wave to the same position on the next wave, the starting point doesn't matter as long as it ends at the same place. Frequency is the number of waves in one period of time. Usually # waves/second. The unit of frequency is **Hz (Hertz) = 1/sec** Period is the number of seconds per 1 wave (# sec/1 wave). **T = 1/f** Wave Speed - how fast the wave is moving. V = d/t = wavelength/period = Wavelength x 1/period. **V = Wavelength x Frequency**. A pulse is a single disturbance. A traveling wave is one that is continuous. Transverse Wave Longitudinal Wave
 * __Notes__**

1a.) In order to change the tension in a vibrating string you add mass or take mass away from the string. 1b.) The more tension there is the higher the pitch, the less tension the lower the pitch. If you plug numbers into the given equation you will find this to be true. 2a.) To change the length of the string you press down on a fret, this cuts the rest of the string off, creating a new length for the string. 2b.) By changing the length of the string the pitch becomes higher. 3a.) In order to keep the pitch the same while changing the tension of the string you need to increase the length proportionally. 3b.) In order to keep the pitch the same while changing the length of the string you need to decrease the tension of the string proportionally. 4.) If length is decreased and tension increases the pitch would increase If length increases and tension decreases the pitch decreases If length increases and tension increases as well the pitch will be lower (if length is increased more) If tension decreased and length decreased the pitch would decrease (if the tension decreased more) 5a.) By pressing down a fret the length of the string decreases. If tension decreased more than the length, the pitch would be lower 5b.) By tightening the strings before playing a note the pitch is higher. 6a.) They tighten or loosen the tension of the strings 6b.) In order to change how the notes sound before a song 6c.)The pitch gets lower because there is less tension 7a.) So the player can change the length of the string in order to change the pitch. 7b.) No, but the players don't need frets, by pressing down the strings are still shortened. 7c.) Violinists need to know where to put there fingers, guitar players have indications of where to put them. 8.) We could have two strings stretched over a cup. One of them could be stretched tight and the other not as tight. We can have a continuous plucking so that the notes will keep playing. To change the notes we can move the cup or stretch the strings more. We can also do this with a few strings of various lengths on different cups. The shorter the strings the high the notes will go.
 * __Physics To Go__**


 * __Physics Plus__**

Today, guitarists change the sound by holding the string that they are playing tighter at different positions on the neck of the guitar, known as frets. The closer the fret is to the body of the guitar the higher it is. There are 6 strings each with different thicknesses, the thicker the string the deeper the sound. In order to play the highest sound you'd use the thinnest string and hold it at the fret closest to the body of the guitar. By shortening the length of the string or creating more tension the pitch increases. By increasing the length of the string or creating less tension the pitch will decrease. This can be proven by plugging numbers into the given equation.
 * __What Do You Think Now?__**

Chapter 5 - Section 2
A girl is surfing at a beach, but not in the water, she is surfing on the waves of a spring.
 * __What Do You See?__**

The water moves towards the shore to make a wave. The speed at the top of the water and the top of the water doesn't stay constant.
 * __What Do You Think?__**

Node: position on a standing wave where there is always __destructive interference__. Antinode: position on a standing wave where there is __constructive interference__. The number of antinodes is called a **Harmonic** n = x (number of harmonic nodes). (i.e. The first harmonic is at the first node) To find the wavelength of a standing wave you need a trough and a crest (like a sine wave) (n/2) wavelengths = length of string (n = number of harmonics) The first harmonic is called the fundamental (you can't get lower than that) Amplitude is how much energy a wave has - Wave property - When 2 separate waves are in the same place at the same time - __Constructive Interference__ is when a crest meets a crest or trough meets trough and the amplitudes add - __Destructive Interference__ is when a crest meets with a trough and amplitudes subtract
 * __Physics Talk__**
 * Interference:**

__**Checking Up**__ 1.) A wave is a transfer of energy through a medium. 2.) A transverse wave has the particles moving up and down but the energy horizontally. A Longitudinal has energy in particles moving in the same direction. 3.) Node is a location of destructive interference or no movement, and anti-node is constructive interference and a fluctuation of height of spring.

1a.) amplitude- measured distance from equilibrium lines wavelength- from one point on a wave to the exact point on another. (two antinodes)  frequency- times in one second or the reciprocal of the period  speed- d/t or wavelength * frquency  1b.) amplitude: meters wavelength: meters frequency: Hertz speed: m/s 1c.) Just wavelength and frequency. As frequency goes up, the wavelength will go down. 2a.) The waves start coming more quickly after one another. 2b.) it makes a smaller wavelength and frequency higher and period gets quicker 2c.) the speed and amplitude will remain the same 3.) Measure one point on a wave and find the exact point on the next and measure the distance between them 4.) Measure how many waves pass a certain point in one second. 5a.) wavelength: meters 5b.) Frequency: hertz 5c.) speed: m/s 5d.) wavelength * period = speed 5e.) wavelength (m) * period (s) = speed (m/s) 6a.) a standing wave is a flow of energy through a medium where certain points (nodes) don't move because of destructive interference, and others (antinodes) move to the maximum amplitude because of constructive interference. 6b.) 6c.) A complete cycle of trough and crest, or count two nodes. 7a.) transverse- vibration of medium and energy flow are perpendicular longitudinal- vibration of particles and energy are parallel  7b.) Transverse would be how a jump rope is moved side to side or up and down, and longitudinal would be pulling part of the spring back and letting it go so it moves without the spring appearing to move. 7c.) The bounce of the wave off the other side of the spring. 8a.) They were proportional. To make the wave length shorter you need to make the frequency proportionally larger. 8b.) To make the wavelength longer you needed to make the frequency proportionally smaller. 9a.) 1- 10 m  2- 5 m  3- 1.66 m  4- 1.25 m  5- 1 m  9b.) They are each the 5 meters divided into how many antinodes there are.  10a.) 20 m  1 antinode= 1/2 wave length 10b.) frequency = 1/period =1/(2)  =1/2  10c.) 10 m/s v=lambda * f =20 * 1/2 v= 10 m/s 11a.) 5 cm amp 1 + amp 2 = center amp  3 cm + 2 cm  11b.) yea, then it would be amp 1 - amp 2 and would = 1 cm in the middle 12.) v=d/t v= 9 m / 2.64  v= 3.41 m/s  13a.) nodes 13b.) 6 m 13c.) 3.5 m
 * __Physics To Go__**


 * __Physics Plus__**
 * whenever a "shape" passes through the middle, whether the "result wave" increases, decreases, or goes away, they continue as they were going before

As the shoreline decreases the amplitude on the bottom decreases, thus making the amplitude on top increase proportionally. The waves energy pushes it forward when there is no more water to travel on (the medium). If instead of a steadily decreasing shore it was in, let's say, a box the wave would bounce off and continue in the other direction instead.
 * __What Do You Think Now?__**

Chapter 5 - Section 3
__**What Do You See?**__ A guy is playing a makeshift instrument with a string stretched over a cup and broom. The string is as good as the harp.

__**What Do You Think?**__ When the tension is greater in the string, the string can vibrate faster when plucked. When the string vibrates faster it creates a higher pitch.

__**Physics Talk**__ The sound we hear from a string vibrating is a standing wave. Pitch is directly related to frequency. Shorter and tighter strings produce a higher pitch. Wavelength and frequency have an inverse relationship. Increased tension means more force to vibrate string. The frequency is v/wavelength which is a direct relationship. Weaker tension makes the wave move slower and a higher tension will make the wave travel fast. The speed of a wave is dependent on the medium it travels through and the length of the string. Wavelength is related to the fundamental string (it's 1/2 the longest possible wavelength). The tension of the string changes the pitch because the higher the tension the more force will be exerted to pull the string back. The more force will provide a bigger acceleration and a bigger vibration therefore a greater speed. Speed and frequency are directly related and if speed goes up, so does frequency. A tighter string will give a higher pitch. A bigger string will produce a lower pitch. The equation is L = n1/2(wavelength)

__**Checking Up**__ 1.) When you decrease the wavelength there needs to be more waves to fill the same string, therefore a higher frequency. f=v/(wavelength), when frequency goes up the wavelength goes down. They are an inverse relation, as one goes up the other must decrease. 2.) The greater the tension the higher the pitch will be. They are directly related. By increasing the tension the pitch tension goes up. A higher tension results in a higher force pulling the string back to its original location from its displacement and a greater acceleration and a greater vibration and a higher speed and a higher frequency and therefore a higher pitch. 3.) An increased tension will make the part of the string that is displaced move with more force and it will accelerate and vibrate faster therefore it will travel down the string faster. 4.) L = n1/2(wavelength)

Resonance- Force something to vibrate at its natural frequency, a standing wave is formed and amplitude increases steadily.
 * __Notes__**

The length of a string is found by multiplying harmonics by half the wavelength. When the tension is greater the pitch is higher because it needs to be higher in order to create the same wave, when the tension is less the pitch will be less because it needs to keep the same resonance to have the same "pure" sound.
 * __What Do You Think Now?__**

Chapter 5 - Section 4
All of the people in the picture are blowing into stuff and making different pitched sounds with these "toys."
 * __What Do You See?__**

For a flute or an organ to create a sound it starts completely open. This allows the "tube" to be the shortest, because the air escapes quicker. There are keys along the side of the flute that you can close which covers up more making the "tube" longer, For an organ each tube that is played is a different length.
 * __What Do You Think?__**