Presentation on theme: "Pg. 24 9/26/13 IQ: What are all of the sounds that you hear in a minute’s time? Write down as many as you can."— Presentation transcript:
1 pg. 249/26/13IQ: What are all of the sounds that you hear in a minute’s time? Write down as many as you can.
2 Sound is a form of energy that travels in waves. What is SOUND? Pg 25Sound is a form of energythat travels inwaves.
3 Sound WavesSound vibrations occur in waves that go out in every directionRepeated patterns of molecules spreading apart and squeezing together.ALL sound is carried through matter (medium) as sound waves
4 How does Sound Travel?When energy causes something to vibrate, molecules in the air crowd together, then spread apart, causing sound waves to travel away from the vibrating object
5 What makes Sound?Vibrations: back and forth motion of particles in matterNo medium=no sound because no vibration occurs
7 IQ: /30/ pg 26Which unit is used to express loudness of a sound wave?
8 Frequency Frequency: How many waves go past a point in a second Measured in HertzThan hereLower Frequency
9 PITCH and FREQUENCY pg 27PITCH: measure of how high or low a sound is perceived to be, depending on the frequency of the sound wave.A high frequency is a high pitch. Ex. ChihuahuaA low frequency is a low pitch. Ex. German Shepherd
10 LOUDNESS and AMPLITUDE Amplitude is how tall the wave is from rest positionWave amplitude is related to loudness (loud or soft).A low amplitude wave has a soft sound.A high amplitude wave has a loud sound.AmplitudeAmplitude
11 DecibelUnit used to express how a loud or soft a sound is perceived
12 Doppler Effect Observed change in frequency and pitch of a sound. Due to the motion of either the sound source or the observer is moving.Ex. Police siren, train, motorcycle going past you
13 OQ: Which two sound properties are responsible for pitch and loudness of sound? Explain why.
14 Pg 28IQ 10/2/13Which medium does sound travel through the fastest?
15 Speed of Sound in Types of Media Gas: (air) travels slowest in gasSpeed of Sound in air 344 m/sLiquids: Sound travels faster in liquids than gas, but slower than in a solidSolids: Travels fastest through solidsSound cannot travel through a vacuum (a space that is “empty” of matter).(Solid) (Liquid) (Gas)
16 REFLECTION Bouncing back of a wave after hitting a barrier Sound Waves have 3 common features:Bouncing back of a wave after hitting a barrierReflected sound waves are called echoesReflects best off of a smooth, hard surface(give examples of where you hear a reflection best)Ex. MirrorEcho1. They:a. Have a set wavelengthb. Vibrate at different speeds--Frequency: the number of complete wavelengths, or times an object vibrates per second.c. Carry Energy--amplitude is the amount of energy a wave has--high amplitude sound is made by objects with great vibrating motion
17 Echolocation Use of reflected sound waves to find objects Animals use echolocation to hunt food/find objects in their path; these sounds have such a high pitch or frequency that the human ear cannot hearBased on how long it takes sound waves to echo back to their ears
18 RefractionWave changes speed as it enters a second medium, causing the wave to bend.
19 AbsorptionSome sound is absorbed and reduced when hitting another surface of passing through another mediumTypes of surface for best absorption: draperies, cloth, etc.Sound-absorbing materials are porous; sound waves entering the tiny air-filled spaces bounce around until their energy is spent.
20 DiffractionWhen a wave passes a barrier or moves through a hole in a barrier it bends and spreads out.Example: We can hear people talking in the hall, even though we can’t see them.
21 Wave SpeedWaves in different mediums travel at different speeds. However, in a given medium and under the same conditions the speed of the wave is constantThe speed, wavelength, and frequency of a wave are related to each other by a mathematical formula.Speed = wavelength x frequencyFrequency = speed/wavelengthWavelength = speed/frequency
22 OQ /2/13What does the speed of the wave mostly depend on?