Lesson 12.1 PDF: Sound Waves

Which BEE SECTION: 12.1 are you? Sound Waves Which BEE HS PS 2-6,4-1 are you? Which Learning BEE are Objective: you? IWBAT Explain how sound waves are produced. Key words Compres...

Which BEE SECTION: 12.1 are you? Sound Waves Which BEE HS PS 2-6,4-1 are you? Which Learning BEE are Objective: you? IWBAT Explain how sound waves are produced. Key words Compression Rarefaction Pitch Doppler Effect  ENGAGE sound waves SECTION: 12.1 Sound Teacher will demonstrate, “How tuning forks can be used?” Waves HS PS 2-6,4-1 Whole class activity: Learning Tunning forks of different frequencies will be given to the students to Objective: create their own experiment to produce sound waves. IWBAT Explain how sound waves are Each Group will share their experiences and produced. write down their observations in their notebook. Key words Compression Rarefaction https://javalab.org/en/tuning Pitch _fork_and_sound_wave_en/ Doppler Effect  EXTEND Class Discussion: SECTION: 12.1 Sound Students will do the class discussion and write down the important Waves points to see the video. HS PS 2-6,4-1 Real life example: Learning How To Use Tuning Forks For Healing Objective: IWBAT Using tuning forks for healing is a very gentle yet Explain how powerful modality to treat the mind, body, and sound waves are soul, and to restore inner balance and health. It produced. works with the nervous system, the tissues, and the Key words more subtle energies of the body, being deeply Compression relaxing, and filled with long-term benefits. Rarefaction Pitch https://www.youtube.com/wa Doppler tch?v=X3kW26L_7dA&t=42s Effect  EXPLAIN The vibrating prong of a tuning fork sets the air molecules near it in motion. SECTION: 12.1 Sound Waves HS PS 2-6,4-1 Learning Objective: IWBAT Explain how sound waves As the prong moves to the are The air molecules in front of left, the molecules to the produced. the movement are forced right spread apart, and the closer together. Such a density and air pressure in Key words region of high molecular this region become lower Compression density and high air pressure than normal. This region of is called compression. lower density and pressure Rarefaction Pitch is called a rarefaction(stretch). Doppler How is the position of the air Effect molecules related to the motion of the prongs over time?  ELABORATE Vibrating object can be represented by a sine curve SECTION: 12.1 In sound waves, the vibrations of air molecules are parallel to the direction Sound of wave motion. Thus, sound waves are longitudinal. The simplest Waves longitudinal wave produced by a vibrating object can be represented by a sine curve. Thus, the sine curve represents the changes in air pressure due HS PS 2-6,4-1 to the propagation of the sound waves. Note that Figure shows an idealized case. This example disregards energy losses(damping) that would Learning Objective: decrease the wave amplitude. IWBAT 1. As a result of a distant explosion, an observer first compression compression compression compression rarefaction senses a ground tremor, then hears the explosion. rarefaction rarefaction Explain how sound waves What accounts for this time lag? are Sound travels faster through the ground. produced. 2. By listening to a band or an orchestra, how can Key words you determine that the Compression speed of sound is the Rarefaction same for all frequencies? Pitch Notes that are played at the Doppler same time reach your ears at the same time because of Effect same medium in which they travel, air.  EXIT TICKET SECTION: 12.1 1.When a part of a sound wave travels from air into water, which property of the Sound wave remains unchanged? Waves A. speed B. frequency B. wavelength D. amplitude HS PS 2-6,4-1 Learning 2.What is the wavelength of the sound wave shown in the figure? Objective: IWBAT A. 1.00 m B. 0.75 m Explain how C. 0.50 m D. 0.25 m sound waves are produced. 3. If a sound seems to be getting louder, which of the following is probably Key words increasing? Compression Rarefaction A. speed of sound B. frequency Pitch C. wavelength D. intensity Doppler Effect 4. Why are sound waves in air because air molecules vibrate in a direction characterized as longitudinal? parallel to the direction of wave motion  ENGAGE speed of sound in various media SECTION: 12.1 ALERT: Sound Listen carefully!!!!!! What is your audible frequency? Waves HS PS 2-6,4-1 Learning Objective: IWBAT Compare the speed of sound in various media. Key words Compression Rarefaction Pitch Doppler Effect  EXTEND What is the range of SECTION: 12.1 average human Sound audible sound Waves waves? HS PS 2-6,4-1 Learning Objective: IWBAT Compare the speed of sound in various media. Key words Compression Rarefaction Pitch Doppler Effect What are the differences between infrasonic, audible, and ultrasonic sound waves?  EXPLAIN Frequency determines pitch SECTION: 12.1 How can we Relate the frequency and pitch? Sound Waves  The frequency of an audible sound wave determines how high or low we perceive the sound to be, which is known as pitch. HS PS 2-6,4-1  As the frequency of a sound wave increases, the pitch rises. Learning Objective: The frequency of a wave is an objective quantity that can be measured, IWBAT while pitch refers to how different frequencies are perceived by the human Explain how ear. sound waves are Pitch depends not only on produced. frequency but also on other Key words factors, such as background Compression noise and loudness. Rarefaction What is the difference between Pitch Doppler frequency and pitch? Effect Frequency is the rate of particle vibration. Pitch is a quality that depends on the listener.  EXPLORE Compare the speed of sound in various media. SECTION: 12.1 The speed of sound depends on the medium. Sound  Because waves consist of particle vibrations, the speed of a wave depends on how quickly Waves one particle can transfer its motion to another particle. For example, sound waves generally travel faster through solids than through gases because the molecules of a solid are closer HS PS 2-6,4-1 together than those of a gas are. Learning Objective: IWBAT Compare the speed of sound in Why can astronauts in space not various communicate using sound? media. A) Sound waves get absorbed in space Key words B) Sound waves require a medium to Compression travel Rarefaction Pitch C) The sound frequency is too high Doppler D) Space contains too much air for sound Effect to travel  EXPLORE The speed of sound also depends SECTION: 12.1 on the temperature of the medium. Sound As temperature rises, the particles of a gas collide Waves more frequently. Thus, in a gas, the disturbance can HS PS 2-6,4-1 spread faster at higher temperatures than at lower temperatures. In liquids and solids, the particles are Learning close enough together that the difference due to Objective: temperature changes is less noticeable. The speed IWBAT of sound does not depend on the pressure of a Compare the speed of medium at a constant temperature. sound travels sound in faster when the humidity is greater. various Sound pulses emitted by a dolphin travel through 20°C media. ocean water at a rate of 1450 m/s. In 20°C air, these pulses Key words would travel 342.9 m/s. How can you account for this Compression difference in speed? Rarefaction Pitch Sound waves travel faster through water than Doppler through air because the molecules of water Effect are closer together and, as a result, can spread vibrations more quickly.  ELABORATE Compare the speed of sound in various media. SECTION: 12.1 Sound What are the factors on which Waves speed of sound depends on? HS PS 2-6,4-1 Explain why the speed of sound increases as the Learning temperature of air rises. Include the role of the air Objective: molecules' kinetic energy in your explanation. IWBAT Compare the speed of The Hot Chocolate Effect sound in various The hot chocolate effect describes the phenomenon media. where the pitch you hear from tapping a cup of hot Key words liquid rises after adding a soluble powder (like cocoa Compression powder into hot water). Stirring in the powder Rarefaction introduces gas bubbles that reduce the speed of sound Pitch of the liquid and lower the frequency (pitch) of the Doppler Effect waves. Once the bubbles clear, the speed of sound and the frequency increase again.  EXIT TICKET SECTION: 12.1 1.Why can a dog hear a sound produced by a dog whistle, but its owner cannot? Sound A. Dogs detect sounds of less intensity than do humans. Waves B. Dogs detect sounds of higher frequency than do humans. C. Dogs detect sounds of lower frequency than do humans. HS PS 2-6,4-1 D. Dogs detect sounds of higher speed than do humans. Learning 2. The greatest value ever achieved for the speed of sound in air is about 1.0 ×10^4 m/s, and Objective: the highest frequency ever produced is about 2.0 ×10^10 Hz. If a single sound wave with this IWBAT speed and frequency were produced, what would its wavelength be? V = f ʎ Compare the F. 5.0 ×10^−6m G. 5.0 ×10^−7m 4. Compare the speed of sound in cold water to warm water speed of and explain the scientific reasons behind this difference. sound in H. 2.0 ×10^6m various J. 2.0 ×10^14m The speed of sound is faster in warm water compared to cold water. media. In warm water, molecules have more kinetic energy and move Key words 3. Which of the following faster. This allows sound waves to be transmitted more quickly from Compression increases the speed of sound in one molecule to another. In cold water, molecules move more air? slowly, which delays the transmission of sound waves. Rarefaction Although cold water is denser than warm water, the increased Pitch A) A decrease in air temperature elasticity (ability to return to its original state) in warm water has a Doppler B) An increase in air pressure greater effect. The elasticity of a medium is a major factor in Effect C) An increase in air temperature determining sound speed. Since warm water is more elastic than D) A decrease in air humidity cold water, sound travels faster in it. SECTION: 12.1 ENGAGE Sound Waves https://www.youtube.com/watch?v=Du9E-Hjw02k HS PS 2-6,4-1 Learning Objective: IWBAT Recognize the Doppler effect and determine the direction of a frequency shift. Key words Compression Rarefaction Pitch Doppler Effect SECTION: 12.1 EXPLAIN THE DOPPLER EFFECT Sound Although the frequency of the siren remains constant, the wave fronts reach Waves an observer in front of the ambulance (Observer A) more often than they HS PS 2-6,4-1 would if the ambulance were stationary. The reason is that the source of the sound waves is moving toward the observer. The speed of sound in the Learning air does not change, because the speed depends only on the temperature Objective: of the air. Thus, the product of wavelength and frequency remains IWBAT constant. Because the wavelength is less, the frequency heard by Observer Recognize A is greater than the source frequency. For the same reason, the wave the Doppler fronts reach an observer behind the ambulance (Observer B) less often effect and than they would if the ambulance were stationary. As a result, the determine the direction of a frequency heard by Observer B As this ambulance moves to the left, frequency is less than the source frequency. Observer A hears the siren at a higher This frequency shift is known as the frequency than the driver does, while shift. Observer B hears a lower frequency. Doppler effect. Key words You are at a street corner and Compression hear an ambulance siren. Rarefaction Without looking, how can you tell Pitch when the ambulance passes by? Doppler The siren’s pitch will drop. Effect SECTION: 12.1 EXTEND Sound waves propagate in three dimensions Sound Sound waves travel away from a vibrating source in all three dimensions. When a musician Waves plays a saxophone in the middle of a room, the resulting sound can be heard throughout the room because the sound waves spread out in all directions. The wave fronts of sound HS PS 2-6,4-1 waves spreading in three dimensions are approximately spherical. The circles represent the centers of compressions, called wave fronts. Learning In this representation of a spherical wave, the wave fronts Objective: represent compressions, and the rays show the direction of IWBAT wave motion. Each wave front corresponds to a crest of the Recognize sine curve. In turn, the sine curve corresponds to a single the Doppler ray. effect and determine the Spherical wave fronts that are a great distance from direction of a the source can be approximated with parallel planes frequency known as plane waves. Any small portion of a shift. spherical wave that is far from the source can be considered a plane wave. Key words Q. Could a portion of no; The wave front Compression must be far from the the innermost wave Rarefaction source (relative to front shown in Figure the wavelength) to Pitch be approximated by be approximated by Doppler a plane wave? Why plane waves. Effect or why not? SECTION: 12.1 EXPLORE Sound Waves HS PS 2-6,4-1 Learning Objective: IWBAT Recognize https://mynoise.net/NoiseMac hines/dolphinsColonySoundsca the Doppler peGenerator.php effect and determine the direction of a frequency shift. Key words Compression Rarefaction Pitch Doppler Effect SECTION: 12.1 EXIT TICKET Sound 1. As a dolphin swims toward a fish, the dolphin sends out sound waves to Waves determine the direction the fish is moving. If the frequency of the reflected waves is higher than that of the emitted waves, is the dolphin catching up HS PS 2-6,4-1 to the fish or falling behind? Learning Objective: The dolphin is catching up to the fish IWBAT Recognize the Doppler 2. Dolphin echolocation is like ultrasound. Reflected sound waves allow effect and a dolphin to form an image of the object that reflected the waves. determine the Dolphins can produce sound waves with frequencies ranging from 0.25 direction of a kHz to 220 kHz, but only those at the upper end of this spectrum are frequency used in echolocation. Explain why high-frequency waves work better shift. than low-frequency waves. Key words Higher frequencies function well in echolocation because Compression their relatively short-wave lengths can detect smaller objects. Rarefaction (Longer wavelengths mean lower frequencies would disperse Pitch around small objects.) Doppler Effect