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Slide 2 Slide 3 What are waves? Def. - Disturbances that carry energy from place to place, through matter or space. Slide 4 Most waves begin with a vibration Waves are made when you speak And heard when you listen Waves can travel through space Waves can make the earth move and shake And make the light you see Slide 5 A medium can be a: is the material in which a wave moves How dolphins communicate wood of a guitar Music from your radio to your ear Slide 6 through medium doesnt move with the wave Energy moves through the medium. The medium just vibrates back and forth and doesnt move with the wave. The medium can move in two ways: 1. Transverse waves 2. Longitudinal waves Slide 7 Medium moves at right angles to the direction of the wave. Ex) football stadium wave A) Crest: highest point B) Trough: lowest point Slide 8 Crest Trough Amplitude Wavelength or Rest position Slide 9 Medium moves parallel to the direction of the wave Ex. a slinky or metal spring A) Compressions: where the molecules are crowded together B) Rarefactions: where the molecules spread apart. Made up of: Slide 10 CompressionWavelength: Compression + Rarefaction Compression Rarefaction Slide 11 Wavelength Wavelength: the distance between a point on one wave and the identical point on the next. (crest to crest, compression to compression) Unit: Unit: meter Symbol: Symbol: Lambda Slide 12 DefDef: the distance from the crest or trough of a wave to the rest position. Directly related to the amount of energy carried.Directly related to the amount of energy carried. Slide 13 Frequency would be3 Hz Frequency would be 3 Hz If 3 waves went by in 1 second You have 3 waves per Second Frequency Frequency: the # of waves that pass one place each second. Unit: hertz (Hz) Slide 14 Slide 15 1.)Type of Medium 2.)Temperature Slide 16 Slide 17 Waves travel fastest in solids, slowest in gases. Solid Liquid Gas Slide 18 Do molecules move faster or slower as temperature increases? So would sound travel faster or slower as temperature increases? Slide 19 Sound waves travel slower than light waves Speed varies, depending on the medium Air = 340 m/s water= 1440 m/s steel = 5000 m/s Slide 20 V= x f Velocity (m/s) Greek lambda Stands for wavelength (m) Frequency (Hz) Slide 21 A tuning fork has a frequency of 280 Hz and the wavelength of the sound produced is 1.5 meters. Calculate the velocity of the wave. Step 1Step 2Step 3Step 4 Slide 22 A wave is moving toward shore with a velocity of 5 m/s. If its frequency is 2.5 Hz, what is its wavelength? Step 1Step 2Step 3Step 4 Slide 23 Earthquakes can produce three types of waves. A typical S wave travels 5000m/s. Its wavelength is about 417m. What is the frequency? Step 1Step 2Step 3Step 4 Slide 24 Slide 25 Wave Behaviors Four typesFour types Wave Behaviors Interference ConstructiveDestructive ReflectionRefractionDiffraction 1.Interference3. Refraction 2.Reflection 4. Diffraction Slide 26 Bouncing back of a wave after it strikes a barrier that does not absorb the energy. An echo is a Sound wave that has been reflected Barrier Slide 27 Angle of incidence = angle of reflection Slide 28 Used to locate underwater objects and distances. ***Reflection** Slide 29 Sonograms: Ultrasonic waves (about 20,000 Hz) used to create images of fetuses in the womb Regular sonogram 3D sonogram Slide 30 RefractionRefraction: Bending of waves due to a change in speed (this occurs because the wave changes mediums) Slide 31 Slide 32 Refraction Why does the pencil appear to be broken when placed in a beaker of water?? Slide 33 Diffraction: Bending of waves around the edge of a barrier Slide 34 Def. - Interference is the result of two or more waves passing through a medium at the same time. There are two types of Wave interference: 1. Constructive Interference 2. Destructive Interference Slide 35 biggerConstructive Interference: two crests meet and make a wave with a bigger amplitude. Slide 36 smallerDestructive Interference: one crest & one trough meet and make a wave with a smaller amplitude.. Slide 37 Slide 38 Def.Def. the study of the science of sound Knowledge of acoustics is important to people who design libraries, concert halls, auditoriums, etc. Slide 39 Longitudinal Wave oscilloscopean oscilloscope is used to convert sound waves into transverse waves, so that we can study them Requires a medium (cannot travel in a vacuum) Slide 40 The highness or lowness of sound. Depends on the frequency of sound waves. High frequency = High pitch Low frequency = Low pitch Slide 41 Human Ear 20Hz-20 000 Hz Infrasonic: below 20 Hz Ultrasonic Sound: above 20,000Hz http://www.ultraso nic-ringtones.com/ Slide 42 Sonograms: Ultrasonic waves (about 20,000 Hz) used to create images of fetuses in the womb Regular sonogram 3D sonogram Slide 43 Supersonic: faster than the speed of sound. A US Navy F/A-18E/F Super Hornet in Transonic Flight Transonic: where only some parts of the air around an object (such as the ends of rotor blades) reach supersonic speeds (typically somewhere between Mach 0.8 and Mach 1.2). Slide 44 An equal mixture of all frequencies of sound http://en.wikipedia.org/wiki/I mage:Whitenoisesound.ogg Slide 45 Change in pitch due to motion. Slide 46 *moving towards increases the pitch *moving away decreases the pitch New word for the day: Dopeler Effect (n) The tendency of stupid ideas to seem smarter when they come at you rapidly. Slide 47 Amount of energy measured in decibels (dB) Depends on the amplitude of sound waves. Large Amplitude = Loud sound Small Amplitude = Soft sound Slide 48 Near total silence - 0 dB A whisper - 15 dB Normal conversation - 60 dB Lawnmower - 90 dB Threshold of pain - 120 dB A rock concert or a jet engine - 120 dB Gunshot, firecracker - 140 dB Near total silence - 0 dB A whisper - 15 dB Normal conversation - 60 dB Lawnmower - 90 dB Threshold of pain - 120 dB A rock concert or a jet engine - 120 dB Gunshot, firecracker - 140 dB Measurement of loudness Slide 49 Displeasing sounds that disrupt the activity or happiness of human or animal life. Causes: Damage to the ear Stress Hearing Loss A sound tube designed to decrease roadway noise