thomma+ch5

'Maurel Thom's Wikilog - Period 6 CP Physics - Burns - 2011

Chapter 5
Section 1

What Do You See An instrument is being made. A string is attached to a weight, and a cup is being used to amplify the sound. The weight creates tension, so the string will vibrate and give off a sound.

What Do You Think Guitarists and violinists make different sound by adjusting the position of their finger on the string. The closer to the to the fret holes the finger are, the higher the note. On a guitar, to make the highest pitch note, you would theoretically put your hand on the lowest string (in relation to the ground) and closest to the sound hole.

frequency = #waves/sec = Hertz period = #sec/1 wave wave speed = v = (lambda)f f = frequency T = tension m = mass of string L = length of string

Increasing mass of string, lower pitch (decr frequency) Thicker strings resonate a lower pitch and thinner strings resonate a higher pitch

Physics Talk vibrate: move back and forth rapidly variable: something that can vary or change during an investigation pitch: how high a low a musical note or sound is to produce sound, something must vibrate shortening a string will increase its pitch. lengthening a string will decrease its pitch

Checking Up 1. When tension is increased, pitch increases because the wave vibrates faster. 2. When you decrease the length of a sting instrument, the pitch increases and sounds higher. 3. Adding mass increased tension, making the pitch higher. 4. When a drum is hit, the head vibrates and we hear it resonate throughout the drums body.

Physics To Go 1. In a string instrument, you can change the tension of a string by tightening the tuning peg, which pulls the string, making it tighter, which would be like adding weight. b) Increasing tension increase pitch. Decreases tension decreases pitch. 2. You can slide your finger closer to the fret hole to increase the pitch or slide your finger closer to the tuning pegs to make the sound lower. b) Shortening the length makes the pitch higher, lengthening the length makes the pitch lower. 3. If you increase the tension, but also increase the length of the string, the pitch should remain the same. b) If you increase the length, but also increase the tension, the pitch should remain the same. 4. The sound would either dramatically change, or not change at all, depending on if increased/ decreased them both, or increased one or decreased the other. 5. The player plays different notes by playing different frets or adjusting the space between their fingers. b) A tuner would increase the tension of a string to raise the pitch or decrease the tension of a string to decrease the pitch 6. The purpose of the tuners is to increase or decrease tension b) To adjust the sound of each string c) As strings stretch, the sound probably decreases. 7. Frets mark position that produce different anti nodes. b). No, bowed-string instruments do not have frets c) Violinists require more accuracy because their is no visual or physical aid that will tell them where the right pitch will come from.

Physics Plus 3. Increasing mass decreases frequency and vibration speed, so the pitch lowers. 4. Thicker strings have a larger mass, so they don't necessarily require a long length. Thin strings need to be long so that the sound isn't too high and is audible.

What Do You Think Now String players add tension to make the pitch higher.

Section 2 What Do You See There is a similarity between waves in a spring and waves in the water

What Do You Think The water moves up and down in a pattern and goes outward from its source.

node: position on a standing wave where there is always destructive interference antinode: position on a standing wave where there is constructive interference n = # antinodes = the harmonic number # 1 harmonic n= 1 n/2(harmonic) = L

Destructive interference is when crest meets with a trough and the amplitudes subtract Constructive interference is when crest meets crest or trough meets trough and the amplitudes add 2

Physics Talk a medium is the substance or material that carries a wave (i.e. a spring) frequency is the number of waves that can vibrate in one second period is the inverse of frequency - the number of seconds it takes for one wave to vibrate a pulse is a single disturbance crest is the highest point of a wave while trough is the lowest a transverse wave is perpendicular a longitudinal wave is parallel harmonic = n = number of ANTI-nodes

Amplitude - meters Frequency - Hertz Speed - m/s

Any point on the wave to the same point of the next wave. To measure frequency, find the number of waves in a second.

Parallel- energy travels vertically, parallel to the floor. Transverse - perpendicular d/t = 9m/2.64s = .0703

Checking Up 1. a wave transfers energy or sound through a vibration or air 2. transverse waves move left to right (perpendicular) while longitudinal waves moves parallel 3. A node is where there is destructive interference and an anti-node is where there is constructive interference. There is no motion in a node and the displacement in an anti-node is its largest.

Physics Plus 10. 20 meters b) frequency = 1/2 c) speed = 10m/s

11. 5meters b) 1 meter below

13. The clothes are at the points of the anti nodes b) 6meters c) 6 or 3 or 1.5. (infinite amount theoretically)





Wave on Board amplitude - 4 meters period - 5 m/s frequency - 1/5 Hertz wavelength - 8 meters wavespeed - 1.6 m/s

Physics To Go 1. The amplitude was in our control at 10, 20, and 30 cm's. Wavelength was measured by using measuring to find one point of the wave to the same point of the next wave. Wave speed was equivalent to the distance over the time. b) amplitude = meters. wavelength = meters. wave speed = m/s c) Both wavelength and wave speed are associated with distance and meters. 2. When you increase the wave speed by shaking the coil faster, frequency increases and waves become shorter. b) The speed of the wave and its length change c) The amplitude does not change, only changing the medium changes the amplitude 3. Wavelength is measured by finding the distance between one point on a wave to the same point on the next wave. 4. Frequency = the number of waves per second. 5. meters b) hertz c) m/s d) wavelength(frequency) e) m/s 6. some points have constructive vibrations, anti nodes, while others have destructive vibrations, nodes.

What Do You Think Now Water moves parallel to make a wave. The energy travels up and down vertically to make a waving motion.

Section 3 What Do You See Two people are plucking string instruments on stage. One girl is playing a harp and one guy is playing a broomstick with a string wired to a box that acts as an amplifier. They are supposed to be an example of standing waves.

What Do You Think Pitch changes with tension because a higher tension gives the string less room to vibrate, creating a higher pitch -and a lower tension gives a string more room to vibrate, creating a lower sound.

Physics Talk a vibrating string producing sound is setting up standing waves between its endpoints. the higher the pitch, the higher the frequency. to get a higher frequency, you have to shorten the sting or generate a higher frequency wave speed = wave frequency x wavelength decreasing the wavelength increases the frequency and pitch inverse relationship: a relationship in which decreasing one variable increases to other, or vice versa if wavelength does not change and frequency increases, than the speed of the wave must have increased increasing the wave speed increases the frequency and pitch direct relationship: increasing/decreasing one variable directly increases/decreases the other variable thicker strings on a piano create lower frequencies

Checking Up 1. Length of string = 1/2(wavelength of the lowest frequency) wave speed = wave frequency x wavelength. if wave speed doesn't change, then frequency must increase. 2. Tension changes the wave speed. Higher tension means the wave and sound travel faster. 3. Higher tension means the the wave will vibrate faster. Lower tension means that the wave will travel and vibrate slower. 4. L = (NxLambda)/2

What Do You Think Now m/s The pitch changes when you change the tension because the two are directly related. More tension means that more frequency is to create a wave. As vibration increases, the pitch increases.

Section 4

What Do You See Kids are trying to play different wind instruments. They are using a jug, straw, an extended trumpet-like pipe, and a girl is whistling through grass.

What Do You Think Flutes produce sound by blowing through a mouthpiece that resonates through a hollow tube with holes. Organ pipes produce deeper sounds with more hollow tubes.