CbrownLetUsEntertainYouChapter5

=Chapter 5= toc

Section 1
There is a girl pulling a spring and its making noise. There is a boy who seems to be affected by the noise and a little dog playing guitar.
 * What do you see?**

Guitarists and violinists make different sounds by tapping or "pulling" the strings that can make noise because of the hollowness of the guitar and/or the violin. By keeping your fingers on certain strings, a guitar player is able to get different pitches to be heard. To make the highest pitched notes the guitar player would have to put his hands as close to where he was strumming.
 * What do you think?**

**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.

**Notes for Section 1 and 2** -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.

**Checking up Questions** 1) As tension increases the pitch gets 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 out of a percussion instrument

**Physics Plus** ƒ=√(T / 4mL) ƒ = frequency T = tension m = mass of string L = length of string If you make the mass of the spring larger (thicker, heavier string) will cause the ƒ to become lower. You could change the note by changing the thickness without having a very long length of string.

**Physics To Go** 1) a. You add or take away mass to the end of the string b. When there is more tension the pitch is higher  2) a. You change the length of a string by holding the string in different positions b. The shorter the string is, the higher the pitch. (Inverse square root relationship) 3) a. If you add more tension in the string, the pitch will stay the same if you make the string longer and vice versa. b. 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. 5) a. 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. b. To tune a guitar you fix the strings and make them either shorter or longer or adjusting it by adding tension. To tune a piano by tightening the knobs which increases the tension  6) a. The purpose of the knobs are that they tighten the strings which add tension. b. Guitars need tuners so you can produce a variety of different sounds and pitches with them. c. The tension becomes lower and the pitch is lower 7) a. The frets on a guitar decide the guitars vibrating length. b. They dont have frets

Guitarists and violinists have thicker and thinner strings on their instruments. This allows high and low sounds to be projected from the instrument. When they shorten the length of the string (guitarists) with their fingers, different sounds are heard. To make the highest pitch sound on a guitar, the air guitarists would put their hands the closest they can together on the instrument. This is because when the string in short a higher pitch comes out.
 * What do you Think Now?**


 * Vocabulary**


 * Crest: Position of maximum amplitude (+A)
 * Trough: Position of minimum amplitude (-A)
 * Amplitude: Represents the amount of energy a wave has (distance)
 * Frequency: (ƒ) how often a wave passes a point in 1 second.
 * # wave / 1 sec = 1/s = Hz (Hertz)
 * Period: (T) how many seconds it takes for 1 wave to pass
 * # sec / 1 wave = s
 * Period and frequency are reciprocals
 * Wavelength: (lambda) Distance from a point on one wave to the same point on the next wave
 * Wave speed = total distance / total time
 * v = lambda / T = lambda x 1 / T = lambdaƒ
 * v = lambdaƒ (wave speed equation)
 * Medium: Substance that carries the wave
 * Transverse Waves: Energy travels perpendicular to particle motion
 * Longitudinal Wave: Energy travels parallel to particle motion
 * Pulse: Single disturbance in medium
 * Wave: Regular and repeating pulses

Section 2
There is a girl on a spring on a surfboard and she is moving like a wave. Shifts in the Earth's plates out at sea cause disturbances in the ocean which causes the water to move. When the wave gets created by the shift from the earth, it gains momentum and breaks causing it to crash and break.
 * What do you see/think?**


 * Physics To Go**
 * 1) a. **** wavelength: The crest to the end of the trough **
 * frequency: The reciprical of the period or the number of waves in the spring **
 * speed: The distance that the spring went and divided it by the time it took to reach that distance or the wave length times frequency **
 * b. amplitude: meters **
 * wavelength: meters **
 * frequency: Hz **
 * speed: m/s **
 * c. Everything is related to each other except for amplitude which was independent. **
 * 2) a. 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. **
 * b. The speed changes. The speed is higher. **
 * c. 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. **
 * 5) a. The units of wavelength are meters **
 * b. The units of frequency are Hertz. It is the number of waves per time 1/time **
 * c. Speed is m/s **
 * d. You can measure the speed with these by the wavelength times the frequency. **
 * e. meters (wavelength) x 1/seconds= meters/ seconds **
 * 7) a. longitudinal waves: energy is parallel to the medium and transverse waves: energy is perpendicular to the medium. **
 * b. back and forth as opposed to side to side **
 * 9) L = N(1/2)lambda **
 * 5=N(1/2)lambda **
 * 10/n=lambda **
 * The wavelength got smaller so the frequency had to get better **
 * 12) Speed= meters/ seconds **
 * speed= 4.5 x 2 x 2.64 **
 * Speed= 9 / 2.64 **
 * 3.41 m/s **
 * 13) They are nodes. **

[[image:[hysics_plu_s_onnee.png width="297" height="426"]] [[image:physics_plus_thererer.png width="292" height="405"]]
 * Physics Plus**

a) Amplitude: 4 m b) Period: 10 s / 2 c = 5 s per cycle c) Frequency: 2 cycles / 10 seconds = .2 hz d) Wavelength: 8 m e) Wave speed: 8 m * .2 hz = 1.6 m/s

Waves are started by an interruption that has a frequency. The amount of times that the interruption happens in the frequency. The medium in the wind that causes the waves to continue moving. This causes an amplitude to be seen in a wave. Ocean waves are transverse.
 * What do you think now?**

Section 3
**What do you see/think?** There are two people playing instruments. The boy is playing a broom with a string attached to a box and the girl is playing a harp. It is showing standing waves that make music. The pitch changes when you change the tension in the string because the tighter the string the higher the sound. There is a smaller amplitude.


 * Physics Talk**
 * **Wavelength, Wave Speed, And Frequency**
 * Frequency and Wavelength
 * Vibrating string : sets up a standing wave
 * The length of the string determines the wavelength of the standing wave
 * v = ƒ (lambda)
 * f = v / ƒ
 * Decreasing the wavelength increases the frequency and pitch
 * Tension and Thickness of a String and Frequency
 * An increase in tension produces a greater acceleration on that portion of the string that is displaced and make it vibrate faster
 * **Direct Relationship:** Increasing the wave speed increases the value of the right side of the equation (v = v/lambda)
 * Increasing the wave speed increases the frequency and pitch
 * L = n * lambda / 2

**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

Pitch and frequency are inversely related and when the pitch gets lower, the frequency increases. When the tension on the string is greater, the string has a harder time producing a wave which affects the pitch also. When the string is shorter, the pitch is higher. When you make the tension greater, the pitch also gets higher. There is less elasticity to the string, so the particles are more responsive. They can react faster than when the tension of the string is tighter. Tension and frequency have a direct square relationship. When you increase tension, the frequency will also increase.
 * What do Think Now?**

Section 4
Flute and organ pipes make noises by the length of the pipe. The shorter the pipe the higher the noise, the longer the pipe the lower the noise. There is a person playing a really long piped instrument that would presumably sound low.
 * What do you see/think?**

__Diffraction:__ Bending of a wave around an obstacle or through an opening. (bending)
 * Physics Talk**

L = n(1/2)lambda L = (1) (1/2) (.784)
 * What length tube would be needed to make a 440 Hz note as the fundamental?**
 * a. open**
 * //L = .392 m//**

v = ƒ * lambda 345 (typical room temp) = 440 * lambda wavelength = .784 m L = n(1/4)lambda L = (1) (1/4) (.784) L = .196 m
 * b. closed**