Chapter+5

=Shana Smolinsky's Wiki- Chapter 5= toc

Section 1
5/6/11

There is a can attached to a string and there is a weight at the end pulling it down. It is like a guitar because to change the sound you add tension. A girl is plucking at the string and a really loud noise is coming out.
 * What do you See?**

Guitarists and violinists change the sound of their guitar by making their strings tighter or looser. They play with the strings in order to produce different sounds. A guitar player would make the highest pitch noises by positioning their fingers right at the front of the string. I think that the strings would need to be far away from the open circle because that produces low sounds from the echo.
 * What do you Think?**

**Road Technician Hw** A sound Technician makes sure that any audio coming from an amp or a microphone is picked up and able to be heard by the audience. They also need to make sure that the singer is heard over the audience. They run all the sound checks for the microphones.

**Physics Talk** Sound is caused from vibrations. Variables are the things that change in an experiment. Length and tension on strings are the variables that cause a change in the pitch of an instrument. Pitch is how high or low the sound is, it has nothing to do with volume. Guitarists for example change their pitch by holding the strings tighter and closer to the front of the guitar if they want to make the pitch higher. As the tension increases, the pitch is higher and as the string is shorter, the pitch is higher. Vibrations cause sound from a percussion instrument.

-The crest is the position of maximum amplitude. -The Trough is the position of minimum amplitude. -The medium is what the wave is transporting through (spring, string, metal, air, water). The substance that carries the wave -The wave length is the period, it is the length of one wave. It is the distance from one position on a wave to the same position on another wave. upside down y is signal -Frequency is the number of waves in one period of time. #of waves/ seconds. The unit is Hertz (Hz=1/s) -Period is frequencies reciprocal. #of seconds over 1 wave (s) T(period)= 1/f -Wave Speed is The rate of travel. how fast a wave is moving -Wave speed equation- V= wavelength x frequency -Pulse is a signal disturbance.
 * Notes for Section 1 and 2**
 * -PHYSICS PLUS: ** f is frequency, T is tension, m is mass of string, L is length of string.... f= sqrt(T/4mL)-- GRAPHS IN NOTEBOOK

**Checking up Questions** 1.) As the tension increases, the pitch is higher. 2.) The pitch is higher when the string is shorter. 3.) The mass increased the tension so the pitch was higher. 4.) Vibrations are what causes sound from a percussion instrument.

Hearing is basically feeling vibrations in a more complex way. Deaf people don't live in a world of silence, they feel the vibrations. It is harder to feel higher frequency vibrations that high frequency vibrations so Dame Evelyn Glennie had to work harder to hear. She felt vibrations through the walls by putting her hands up against the wall while her teacher played notes. This is how she learned and heard things, through the vibrations.
 * Inquiring Further**

1a.) You add or take away more mass to the end of the string to increase the tension. 1b.) When there is more tension the pitch is higher. 2a.) You change the length of a string by holding the string in different positions. 2b.) The shorter the string is, the higher the pitch is. 3a.) If you add more tension in the string, the pitch will stay the same if you make the string longer and vice versa. 3b.) The shorter the string is the less tension you need to keep the pitch the same. 4.) If you changed both, the pitch would either be higher lower or the same depending on how you changed each. 5a.) They are able to play different notes after it is tune because they change the tension and the length of the strings which changes the sound. 5b.) To tune a guitar you fix the strings and make them either shorter or longer. You also adjust it by adding tension. To tune a piano by tightening the knobs which increases the tension 6a.) The purpose of the knobs are that they tighten the strings which add tension. 6b.) Guitars need tuners so you can produce a variety of different sounds and pitches with them. 6c.) The tension becomes weaker and the pitch is lower 7a.) The frets on a guitar decide the guitars vibrating length. 7b.)They dont have frets. 7c.) They need more finger accuracy because there are a lot more strings on each so you need to make sure you get the right pitch.
 * Physics To Go**

Guitarists and violinists make different sounds by tuning their instruments. They hold the strings to make them shorter and tighten them with the knobs if they want to pitch to be higher. To make the pitch lower their do the opposite. if someone where playing the airguitar and trying to make high pitched noises, they would hold their fingers to make the strings as short as possible.
 * What do you Think Now?**

**Section 2**
The girl is surfing on the waves of a spring and it looks like the waves of the water. There are similarities between the two.
 * What do you See?**

The water moves to make a wave because the top of the wave is moving faster than the second part of the wave so it crashes down on shore over the bottom of the wave.
 * What do you Think?**

A wave is the transfer of energy without a net transfer of mass. To transfer energy through a certain object, you have to use chemical or mechanical energy. The energy is then transferred to the object. The medium is the material that the energy is transferred through. The medium for a water wave for example is the surface of the water. Waves continue to travel unchanged by the wave ahead of them. A periodic wave is a repetitive series of pulses. It keeps repeating after a certain amount of time. The crest is the highest point on a wave and the trough is the lowest point. The amplitude is the highest displacement of the wave. It is equal to the height of the crest. The wavelength is the distance from one point on the wave to the same point on another wave. The frequency is the number of vibrations over a given amount of time. The period is the amount of time it takes the wave to complete one full cycle. Period= 1/frequency. Frequency= 1/Period. They are inversely related. A transverse wave is when the direction of the medium is perpendicular to the direction of the wave. In a compressional wave they are parallel. A standing wave is a wave pattern that moves in a constant position. The node is the spot on the wave where the standing wave is motionless. It is the position where there is always destructive interference. An antinode is where the displacement is the biggest on a standing wave. It is the position on a standing wave where htere is constructive interference. On a wave it is the part that is open, the node is the pinched in part. The speed of a wave is distance over time. The number of waves is that number harmonic. The length of a string= n(1/2) lambda. The higher the harmonic, the higher the pitch. Interference is a wave property. It is when two separate waves are in the same place at the same time. When the waves amplitude of a crest and a tough are in two different directions and amplitudes subtractl, that is destructive interference. Constructive interference is when crest meets crest or trough meets trough and the amplitudes add.
 * Physics Talk Summary**

1.) A wave is the transfer of energy through an object without the net transfer of mass. 2.) A transverse wave is when the direction of the medium is perpendicular to the direction of the wave, and a compressional wave is where the medium is parallel to the direction of the wave. 3.) A node is the motionless spot on a standing wave and an antinode is where there is the biggest displacement on a standing wave.
 * Checking Up Questions**

1a.) amplitude- We measured 10 centimeters out, 20 centimeters out, and 30 centimeters out. That ended up being our amplitude. wavelength- The crest to the end of the trough.  frequency-The reciprical of the period or the number of waves in the spring  speed- We took the distance that the spring went and divided it by the time it took to reach that distance. or wave length times frequency  1b.) amplitude- meters wavelength- meters frequency- Hz speed- m/s 1c.) Everything is related to each other except for amplitude which was independent. 2a.) As you shake the coiled spring more rapidly, the frequency changes, it becomes higher, so the wave length is shorter. The medium changes the speed. 2b.) The speed changes. The speed is higher. 2c.) The amplitude of the wave stays the same. 3.) You can measure the wave length by measuring from one point on the wave to the same point on another wave. 4.) The frequency is the number of vibrations over time. You would be able to measure the frequency by seeing how many waves are made compared to the amount of time you were recording. 5a.) The units of wavelength are meters 5b.) The units of frequency are Hertz. It is the number of waves per time 1/time 5c.) Speed is m/s 5d.) You can measure the speed with these by the wavelength times the frequency. 5e.) meters (wavelength) x 1/seconds= meters/ seconds 6a.) A standing wave is a wave that remains in constant position as it follows a pattern. 6b.) 6c.) You can find the wave length by measuring from one position on the wave to the same position on another wave because the pattern is constant. 7a.) longitudinal waves are ones where the energy is parallel to the medium and a transverse wave is one where the energy is perpendicular to the medium. 7b.) Coiled springs can be either. They can be a transverse wave if the person is moving it from side to side, left and right. They can be longitudinal if the person pushes to spring forward and backwards. 8a.) To make the wavelength shorter i would increase the frequency by shaking the spring more rapidly. 8b.) I would do the opposite to make it longer. I would decrease the frequency by shaking the spring slower. 9a.) 1 meter, 2 meters, 3 meters, 4 meters, 5 meters 9b.) The frequency and the wave patterns are related to each other because the more wave patters that are made, the higher the frequency 10a.) 20 meters 10b.) The period is 2- frequency is reciprocal. The frequency is 1/2 Hz 10c.) speed= distance/ time  speed= 20/2  speed= 10 m/s  11.) 3 meters+ 2 meters 5 meters- amplitude 11b.) If they were in opposite directions you would subtract them and the amplitude would be one meter. 12.) Speed= meters/ seconds speed= 4.5(2)/2.64 Speed= 9/2.64 3.41 m/s 13a.) The node is the position they are in 13b.) It is 6 meters- 3 meters+3 meters 13c.) It could also be 3 or 1.5 because it could be split in half.
 * Physics To Go**


 * Notes**

**Active Physics Plus**

All waves' particles just go up and down. The energy is the actual wave so the source of the wave is the initial shake so the water or whatever material goes apart from the middle.
 * Essential Question**

**What do you Think Now?** Water moves to make a wave because wind is the medium. It travels perpendicular to the medium so it is transverse. The water moves up and down as well so there is an amplitude.

Section 3
Two people are playing different instruments. One is playing a harp with a lot of different strings. The other is just playing with one string.
 * What do you See?**

Pitch gets higher when you make the string shorter.
 * What do Think?**

The length of the string determines the wavelength. The wavelength is double it. To get a higher frequency, shorten the string. Wave speed is length times frequency. In an inverse relationship, when one decreases, the other increases. Frequency the shorter the wavelength- this is an inverse relationship. Increasing tension doesn't affect wave length. The frequency increases though so the wave speed does too. The larger the tension, the larger the acceleration so the strings will vibrate faster. When the wave speed increases so does the frequency and pitch. This is a direct relationship. As one goes up so does the other. The thicker the string, the slower the vibrations travel down. L(length)= n(number) x lambda/ 2 T= time of vibrations/ 10 frequency= number of vibrations/ time
 * Physics Talk**

**Checking up Questions** 1.) When the wave length is smaller the frequency is higher. The equation is lamda= 2L/n 2.) As the tension increases, the pitch increases. The more the tension, the larger the accelerations so the strings vibrate faster. That increases the pitch. 3.) The higher the tension, the higher the frequency. As the frequency increases, the wave speed increases. 4.) L= n x lambda /2

When the tension of the string is heavier, it makes it harder for the string to produce a wave which affects the pitch. The pitch gets lower as the frequency increases.
 * What do Think Now?**

Section 4
People are playing different wind instruments. Different sounds are coming out of all of them. The ones that are blowing on the shorter instruments seem to be blowing harder than the other.
 * What do you see?**

When you blow into the instrument and cover up some of the holes, the sound either travels farther or shorter. This changes the length of the instrument and therefore changes the pitch.
 * What do you Think Now?**

**Physics Talk Summary** Sound is a compressional wave. It compresses together then pushes out like a spring. THe medium that sound travels through is air. At the bottom of a test tube there is no vibration and the amplitude is zero so there is no sound. It is at the node of a wave. At the open end, it is the loudest it can go and the amplitude is at its maximum. This is the antinode of a wave. Sound waves travel by moving around barriers. DIffraction is this ability for the waves to be able to bend, spread out and change direction in order to get into an opening. The smaller the opening the more diffraction. The size of the opening determines the wavelength and volume. If both ends of a tube are open, it forms a vibrating column of air. The displacement of the air molecules are zero. When one end is closed, the pitch and frequency decrease. If the both ends are open it is 1/2 lambda. The Wavelength is double then if it were closed.

1.) The medium is air. Sound travels through the air using diffraction. It travels in wave form and is able to get through openings in order to be heard. 2.) Waves diffract by finding openings and bending and changing directions in order to get through them. 3.) The speed of a wave is the wavelength times the frequency. If the wave speed is constant than the frequency and wavelength are constant to.
 * Checking up Questions**

**Physics to Go** 1a.)They both produce waves 1b.) Plucking a string is compressional and blowing into a pipe is transverse. 3a.) It is 11 meters 3b.)

3c.) L= n(1/2)lamda L=1(1/2)lamda  19=1/2 lamda  It is two times the length. 22 m.  3d.)The larger the wavelength the lower the frequency because there is only one antinode 4a.) It is 12 meters long. 4b.) v=frequency (wavelength) 340= 12(frequency) frequency= 28.3 Hz 4c.) It is 6. It is double because it is open.  4d.) v=frequency (wavelength) 340= frequency(6) frequency= 56.7 Hz 5.) It will be 4 meters long and the frequency is a lot greater. It is 85 Hz.  6a.) It is called diffraction 6b.) 7.) v=d/t 340= 1600/t t=4.71 s

**Notes**