Chapter+5

= =

=toc Section 1=

There is a string going across a a can and there is weight hanging from a pulley and this is is changing the tention. It is making a very loud sound because the boy seems to be very surprised at how loud it is. Guitarists and Violinists make different sounds by depending on how tight or loose the strings are and where their fingers are positioned. To make the highest pitch noise on a guitar you position your fingers high on it.
 * What do you see?**
 * What do you think?**

If you are a sound technician you are in charge of handling the sounds and making them come across as clear as possible. They adjust the volume levels and make sure certain things are louder than others that have to be. They are in charge with handling the sounds that work with microphones as well as other audio tools that are used.
 * Homework:**


 * Physics Talk**
 * Vibrate- move back and forth rapidly
 * variable- something that can change or vary during an investigation
 * pitch- how high or low a note is
 * increasing the hanging mass tightened the string by creating more tension in it.
 * As the string increased, the pitch of the sound also creased.
 * Increasing the tension or decreasing the length of the string will increase the pitch.


 * Notes from class**
 * pitch increases when tension increases and when length of string decreases
 * equilibrium position of the string is when is it straight across with no curves
 * the crest is the top of the wave [position of maximum amplitude]
 * the trough is the bottom of the wave [position of minimum amplitude]
 * These are called a traveling wave
 * medium: the substance that carries the wave
 * wavelength- the distance from one position of a wave to the same position on the next wave (upside down y)
 * frequency- the number of waves/ seconds (cycles per second) (Hz=1/s)
 * period- # seconds/ 1 wave T= 1/f
 * wave speed- how fast the wave is moving wave speed equation is v= (frequency)(f)
 * traveling wave- is a wave that continues to move and continues to be created
 * pulse- a single disturbance
 * transverse wave
 * longitudinal wave

1. What happens to the pitch of the sound produced by a string when its tension is increased? **When the tension increases, the pitch gets higher.**
 * Checking up Questions**

2. When you decrease the length of a string in an instrument, how does the pitch of the sound you hear change? **The sound becomes more high pitched**

3. What effect did adding mass to the mass hanger have on the string in the investigate?  **It have the string more tension, since the string had more tension it created a higher pitch of a sound.**

 4. How is sound produced in a percussion instrument?
 * It vibrates creating a sound.**


 * PHYSICS PLUS**

If you increase the mass of the string you will get a lower pitch (decrease frequency)
 * 1.**
 * 2.**
 * 3.** To double the frequency you have to quadruple it ,4X the tension and 1/4 decrease length to increase the frequency


 * 4.** Different thickness of wires are used in pianos because when they are hit some provide higher frequency than others, which provides different sounds. If you didn't change the m and the L, then some of the strings would be too long that they wouldn't fit in the piano. You want to use thinner wires so they can still be short but still adjustable, if you only used thin wires then you wouldn't be able to get the range of sounds that you want.

1a) **You can change the tension on a vibrating string by adding mass to the string because the more mass you add the more tension there is going to be on the string.** 1b) **Changing the tension will change the sound. If the tension is less than the pitch is going to be lower and if the tension is greater than the pitch is going to be higher.**
 * Physics To Go**

2a)**You can change the length of a string on a guitar or violin. If you want a high pitch then you have the press down closer to the top of the string.** 2b) **When you change the length of the string it makes it vibrate more which makes a higher pitch.**

3a) **You can change the tension of the string and keep the pitch equal by tightening the strings on the guitar.** 3b)**You can change the length of the string and keep the pitch the same by moving your fingers on the frets.**

4. **If you change the length and the tension of a string at the same time the pitch either gets very high or very low. If you increase the tension and decrease the length of the string the pitch increases to very high. If you decrease the tension and decrease the length of the string the pitch would be very low.**

5a**. Making the strings longer and shorter create different pitches, when a performer wants to play different notes on a guitar and violin.** 5b. **Turners for instruments make the tension on the string either larger or smaller. If you tune the strings really tight the pitch is going to be very high and very tight.**

6a**. Tuners change the tensions which change the pitches.** 6b. **Guitars need tuners because if the strings get too loose you won't be able to produce the sound that you want.** 6c**. When the string stretches the tension because less making the pitch deep.**

7a**. The frets on a guitar make the string longer or shorter because you are switching where your fingers are located.** 7b**. They do not have frets.** 7c**. They need more finger accuracy because there are a lot more strings on each so you need to make sure that you have placed your fingers in the correct position.**

Guitarists and Violinists today make different sounds by changing the lengths and mass of the different strings. Depending on the lengths and masses the strings produce different sounds, either with a high pitch or a low pitch. You are able to get a variety of different sounds to make music. If someone were to pretend to play a guitar they would position their fingers lowers, with the strings shorter to make a high pitch noise.
 * What do you think now?**

= = =**Section 2**=

There is a girl that is surfing on a surf board is in front of the oceans waves. This shows that their is a similarly between a sound wave and an ocean wave.
 * What do you see?**

Water moves to make waves because it travels in an up and down motion and this creates the movement of the waves.
 * What do you think?**


 * Physics Talk**
 * node- position on a standing wave where there is always destructive interference (always one more node)
 * antinode- position on a standing wave where there is a constructive interference
 * the number of antinodes is called a harmonic
 * (n)(1/2)(wavelength)=L
 * interference- when two separate waves are in the same place at the same time
 * 1st harmonic= fundamental
 * destructive interference- is when the crest meets with the trough and reduces the amplitude and amplitudes subtract
 * constructive interference- when crest meets crest or trough meets trough and the amplitudes add.
 * __Transverse wave__ a wave in which the motion of the medium is perpendicular to the motion of the wave.
 * __Longitudinal wave__ a wave in which the motion of the medium is parallel to the direction of the motion of the wave.
 * __Standing wave__ a wave pattern that remains in a constant position (also called a stationary wave pattern)
 * __Node__ a point on a standing wave where the medium is motionless
 * __Antinode__ a point on a standing wave where the displacement is the largest.
 * Node and antinode have to do with standing waves. When two waves intersect it is a standing wave.
 * The medium is what affects the speed of a wave.

1. What is a wave?  **A wave is** **a transfer of energy with no transfers of mass.**
 * Checking Up Questions**

2. What is the difference between a transverse and a longitudinal wave?
 * A longitudinal wave is a wave when the medium of the motion is parallel to the direction of the motion of the wave and transverse waves are waves when the motion of the medium is perpendicular to the motion of the wave.**

3. What is the difference between a node and an antinode? **A node is** **a point on a standing wave where the medium is motionless and an antinode is** **the point with the biggest displacement on a standing wave.**

1a) **To measure the amplitude you have to measure the equilibrium to the crest. You measure the wavelength you have to find the point where you started and then where the pulse is on the wave. Measure this from one crest to one through. To measure frequency you must count how many waves were in the spring per second (this is equation).** 1b) **amplitude is measured in meters, wavelength is measured in meters, frequency is measure in hertz, and speed is measured in meters per second.** 1c) **amplitude is not related**
 * Physics To Go**

2a) **If you shake it faster, it changes the frequency which results in making the wave length shorter. You can only change the wave speed if you change the medium.** 2b) **The speed changes and becomes quicker.** 2c) **The amplitude will stay the same because it does not effect speed.**

3. **You could measure wave length from any point of one wave to the exact same on the next wave.**

4. **To measure the frequency you would need to find how many waves per one second. You can find the amount of waves by comparing the amount of waves in a certain period of time.**

5a) **Wave length is measure in meters.** 5b) **Frequency is measured in hertz.** 5c) **Speed is measured in meters per second** 5d) **You can measure speed by the distance of the medium over the time of one wave.** 5e) **wave length times 1/time, same as meters/seconds**

6a) **A standing wave**  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) **L****ongitudinal waves is the energy and the vibration of the wave is parallel to the medium and in** **transverse waves it is perpendicular to the medium.** 7b) **They can be either transverse or longitudinal. It would be a transverse wave if you were moving the spring from side to side and it would longitudinal if it was moving up and down.**

8a) **To make the wavelength shorter you should shake it less hard.**  8b) **To make the wave length longer you should shake the coil harder.**

 9a) <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">**The wavelengths would be 1** <span style="color: #1035cb; font-family: arial,helvetica,sans-serif;">** meter, 2 meters, 3 meters, 4 meters, 5 meters **  <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 9b) **The frequency of the antinodes that have the longer wave lengths are going to be higher. The antinodes with shorter wave lengths are going to be lower.**

<span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 10a) **20** **meters** <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">10b) **The frequency is 1/2 Hz** <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 10c)<span style="font-family: arial,helvetica,sans-serif; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> **v= (wavelength)(frequency)**  **= 20 (1/2)**  **= 10 m/s**

<span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 11a) **The amplitude would be 5 if they were both crests.** <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 11b) **If one was a crest and one was a trough the amplitude would be 1.**

12.
 * v=d/t**
 * =9/2.64**
 * = 3.04 m/s**

<span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px; padding: 0px;">13a) **nodes is the terms for the positions occupied by the clothes** <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px; padding: 0px;"> 13b) **wavelength would be 6 m** <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px; padding: 0px;"> 13c) **It could also be 3 and 1.5**

<span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px; padding: 0px;">**extra question from board:** <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px; padding: 0px;">**FIND THE FOLLOWING...**

**amplitude:** 4 m **period:** 5 sec **frequency:** 1/5 Hz **wavelength:** 8 m  **wave speed:** (.2)(8) = 1.6 m/s


 * Physics Plus**

Water moves to make waves because wind serves as the medium. It travels perpendicular to the medium so it is a transverse wave.
 * What do you think now?**


 * EXTRA NOTES:**
 * Resonance:** when you force something to vibrate at its natural frequency, a standing wave is formed and the amplitude increases steadily

= = =**Section 3**=

What do you see?
 * There is a stage and two people are performing. One is playing an actual instrument and the other looks like they created theirs. It is a broom attached to a box with some kind of string or spring. It is showing that you can make sounds with other things, not just actual instruments.**

What do you think?
 * I think the pitch changes when you change the tension in the string because the lengths of the instruments change.**


 * Physics Talk**
 * **Inverse relationship****: a relationship in which decreasing one variable increases the other variable or vice versa.**
 * **Direct relationship****: a relationship in which increasing one variable increases the other variable or decreasing one variable also decreases the other variable.**
 * **Increasing the wave speed increases the frequency and pitch.**
 * **Decreasing the wavelength increases the frequency and pitch.**


 * Checking Up Questions**

<span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">**1. How does decreasing the wavelength increase the frequency of a wave? Explain, using an equation that relates the two variables of frequency and wavelength to wave speed.** <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">The length of the string always remains 1/2 of the wavelength of the lowest frequency of a standing wave. The higher the pitch the higher the frequency will be. <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">**2. How is the tension of a string related to its pitch?** <span style="font-family: arial,helvetica,sans-serif;"> When the tension increases then the pitch also increases.

<span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">**3. Explain how tension relates to wave speed.** The higher the tension is then the higher the frequency will be. When the frequency increases so does the wave speed. <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">**4. What is the equation that relates the length of a coiled spring and the wavelengths of the standing waves that can be produced on the spring?** L : n X lambda /2

What do you think now?
 * The pitch changes when you change the tension in the string because when you change the tension it also allows the string to vibrate quicker which makes the wave speed larger. This all effects the pitch, making it higher.**

=**Section 4**=

I see 4 different people and they are all making different sounds with different instruments. One person is blowing into a bottle, and it is creating a sound, someone is is blowing into a strong and someone else is blowing into a tuba and the lest person is blowing into her thumbs with a piece of grass. These are all different wind instruments.
 * What do you see?**

I think that flutes and organ pipes produce sound because there are standing waves inside all of these instruments. The sounding waves produce different sounds.
 * What do you think?**


 * Physics Talk**
 * __**Diffraction**__**: the bending of a wave around an obstacle or through an opening**
 * **Sound waves are standing waves that come to your ears to make you hear different sounds**
 * **they bend and spread out through openings**
 * **The smaller the opening the more the sound waves diffract**
 * **The diffractions of the sound waves as they change from two openings change depending on how large the wave is and where it is starting.**

1. How does sound travel through air?
 * Checking Up Questions**
 * Sound waves travel through the air by spreading out or bending around barriers. Sound waves can spread then spread out and change once them come into a new opening.**

2. How do sound waves diffract?
 * As sound waves spread out or change direction they diffract.**

3. How do you express the speed of a wave in terms of its wavelength and its frequency. What is the relationship between wave frequency and wavelength if wave speed remains constant?
 * A smaller opening produces more diffraction than a larger opening does. The size of the opening is dependant of the wavelength of the sound waves.**


 * PTG**

1a) **Plucking a string and blowing into a pipe both make similar sounds because they both make waves and waves make sounds for you to hear.** 1b) **They are different because a string is compressional and a tube is a transverse wave.**

3a)**The longest organ pipe is 11 meters long.** 3b) 3c) **One antinode is 11 meters long so a full wave is 22 meters long.** 3d) **When you have a longer wavelength everything moves slower, the speed of sounds is slower which makes the pitch lower all because the vibration is slower.**

4a) **3x4 = 12 meters long** 4b) **340/12 = 28.3 hertz** 4c) (**3)(2)= 6 meters** 4d) **340/6 = 56 hertz**

5. **340/4 = 85 hertz**

6a) **When a wave spreads or travels it is called diffraction.** 6b)

7. **v=d/t**
 * 340 = 1600 m/t**
 * t= 4.71 s**


 * What do you think now?**