Chapter+5

=Chapter 5:= toc Sound and light Section 1: What do you see? A girl plucking the string and its really loud. What do you think? They change the tightness of the spring. You would place your fingers near the farthest part of the guitar. What does a sound technician do? They make sure the audio and sound are picked up by the microphone and processed properly. They have to make sure the singer can be heard above all the other instruments. Physics Talk: Vibrate: move back and forth rapidly. Variable: something that can change or vary during an investigation. Pitch: (in music) how high or low a note is. When you add mass to the string it will change the pitch. Increasing the mass the sound is increased. When you change the length the sound changes. The shorter the string the higher the sound. pitch increases when tension increases and when length of spring decreases. crest is position of max amplitude. Equilibrum is the position of the spring. Trough : position of min amplitude. medium: the substance that carries the wave. wave length: is the distance from one position of the wave to the same position on the next wave. frequency: the number of waves in one period of time/seconds. (Hz) T= 1/f wave speed- how fast a wave is moving. V= wave length ( frequency ) Pulse-single disturbance wave- a series of disturbances. transverse wave- long Checking up 1. What happens to the pitch of the sound produced by a string when its tension is increased? The pitch of the sound is also increased. 2. when you decrease the length of a string in an instrument, how does the pitch of the sound you hear change. When you decrease the string the sound become higher. 3. What effect did adding mass to the mass hanger have on the spring in the investigate. Increase the pitch. 4. How is sound produced in a percussion instrument? The object that it strucks vibrates.
 * 1) sec/1 wave= period

PTG: 1. You can change the tension by changing the mass. b) The tighter the tension the higher the pitch. 2. You can press down on the strings which would create more tension and shortening the length. b) The shorter the string the higher the sound because there is more vibration taking place. 3. All you have to do is increase the tension b) make the length longer. 4. If you increase the tension and increase the length the sound will be lower. If you shorten the length and decrease the tension the pitch will become higher. 5. A performer puts their fingers on different spots and puts different pressure on different parts of the guitar to make different sounds. b) They change the tension of the strings. 6. The purpose of the knobs are to tighten or to loosen the tension of the strings. b) There strings become loose and becomes out of tune. c) The pitch becomes lower. 7. The frets determine the guitars vibrating length. b.) They dont have frets c)THey need more accuracy because there is a lot more strings, so you need to make sure you are able to get the right pitch.

What do you think now? To make the sound higher, place your fingers to the side with the tuners. The shorter the strings the higher the sound will be. They make different sounds by moving there hand up and down their instruments making the strings either long or shorter.

Section 2: Someone surfing in the ocean. There is some similarities between the wave lengths and wave lengths on a spring. What do you think? The water moves up and down in waves as it nears the shore. Physics talk: Wave: a transfer energy with no net transfer of mass. __Medium__: the material through which a wave can travel. __Periodic wave__: a repetitive series of pulses; a wave sequence in which the particles od the medium undergo periodic motion:that is, after a fixed amount of time, the medium returns to its starting point and then repeats its oscillation. __Crest__: the highest point of displacement of a wave. __Trough:__ the lowest point of displacement of a wave. __Amplitude__ : the maximum displacement of a particle as a wave passes the height of a wave crest; it is related to the wave's energy. __Wavelength__: the distance between two identical points in consecutive cycles of a wave length. __Frequency__: the number of waves produced per unit time; the frequency is the reciprocal of the amount of time it takes for a single wavelength to pass a point. Period: the time required to complete one cycle of a wave. __Transverse wave__: a wave in which the motion of the medium is perpendicular to the motion of the wave. __Longitudinal (compressional) wave:__ a wave in which the motion of the medium id 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.Where there is always destructive interference. Antinode: a point on a standing wave where the displacement is the largest.(constructive interference).Interference is a wave property- when two separate waves are in the same place at the same time(add). destructive interference is when a crest meets with a trough and reduces the amph. (subtract) n(1/2)landa=L(wave length)

Checking up: 1. What is a wave? a wave is a transfer of energy with no net transfer of mass. 2. What is the difference between a transverse and a longitudinal wave? A tranverse wave is a wave in which the motion of the medium is perpendicular to the motion of the wave. A longitudinal wave is a wave which the motion of the medium is parallel to the direction of 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. An antinode is a point standing wave where the displacement is the largest. PTG: 1.a)to measure the ampilutude: measure distance from equilbrum to creast. wave length: distance from where you started to where the pulse is. frequency: count how many waves were in the spring speed:distance divided by total time. b) amplitude M wave length: m frequency :Hz speed m/s c) everything except amplitude. 2 It changes the frequency- shorter wave length if you have a higher frequency. b) Speed changes c) amplitude doesnt change 3. Any point on the wave to the same point on the next wave. 4. find out how many waves there are in one second. (use a timer) 5. wavelength: meters b)frequency: hertz c)speed is:m/s 6. a) a standing wave is a wave that remains constant and follows a pattern. b) 7. longitudinal the energy and vibration are parallel to each other. b) coiled springs can be either. They can be transverse if the person is moving side to side, or longitudinal if the person pushes the spring back and forth. 8. to make the wavelength shorter increase the frequency be shaking the spring faster. b) to make it longer, decrease the frequency by shaking the spring slower. 9. wave patterns and frequency are related to each other because the more wave patterns the higher the frequency. 10 a) 20 meters b) 1/2 c) 10 m/s 11. a) you would add them and they would be 5 m b) if they were going opposite sides it would be 1 m because you would subtract them. 12. d/t=9/2.6= 3.41 13.a) nodes b) 6m c)it could be 3 or 1.5 becuase it could be split in half. Physics plus:



aplitude: period: frequency: wavelength: wave speed: time is 10s

What do you think now? Water up and down but the wind is the medium that moves perpendicular to the water. This would make it traversal.

Section 3:

What do you see?one kid is playing a harp and the other is playing a one string instrument. what do you think now? Pitch gets higher when you make the string shorter. Physics Talk? inverse relationship: a relationship is 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. The length determines the waves length of a standing wave. Class notes: **Resonance:** When you force something to vibrate at its natural frequency, a **standing wave** is formed and the amplitude increases steadily. (pushing someone in a swing. As you push at the natural frequency you cause the amplitude to grow and grow)

Checking up. 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

What do you think now? An increased tension produces a larger force. This will make it vibrate faster creating a higher pitch. This is a direct relationship. when you increase one variable the other variable increases as well. increasing the wave speed increases the frequency and pitch.

Section 4 What do you see? They are using household items as instruments to make noises.They are all wind instruments. What do you think? The tubes tunnel the energy waves and the air comes out of different holes on the instrument. class notes: Diffraction: the bending of a wave around an obstacle or through an opening. The space must be about the same as the wavelength or smaller.

Physics Talk: diffraction: the ability of sound waves to spread out or change direction as they emerge from an opening. Checking up: 1. how does sound travel through the air? 2. how does sound waves 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 the wave speed remains constant? PTG: 1 3. a) the longest organ pipe is 11m b) c) 4. a) 12 meters long b) c) 6 meters long 5. 6. 7. 340=1600m/t t=4.71s