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SOUND. Can You Hear Me Now ?. GOAL 5 : Students will describe the characteristics of and investigate Wave Motion , Sound , and Light . Objective 1 : Differentiate between Transverse and Longitudinal Waves. Objective 2 : Describe the relationship between
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SOUND Can You Hear Me Now?
GOAL 5: Students will describe the characteristics of and investigate Wave Motion, Sound, and Light. • Objective 1: Differentiate between Transverse • and Longitudinal Waves. • Objective 2: Describe the relationship between • Speed of a Wave, Frequency of a Wave, and • Wavelength. • Objective 3: Investigate the nature of Sound in terms of • Wave Motion.
WAVES are caused by VIBRATIONS • SOUND is produced by an object that VIBRATES. • SOUND WAVES are COMPRESSIONAL WAVES • A SOUND WAVE moves through matter as collisions between the molecules in the matter transfers ENERGY from place to place.
SPEED OF SOUND • SOUND WAVES travel at different speeds through different MEDIUMS and at different TEMPERATURES. • SOUND WAVES CANNOT travel through empty space where there are no particles to collide with. • SPEED OF SOUND IN AIR: • approx. 343 m/s (767 mph) • SPEED OF SOUND IN WATER: • approx. 1,498 m/s (3,350 mph) • SPEED OF SOUND IN STEEL: • approx. 5,200 m/s (11,632 mph) • SOUND WAVES travel FASTER • in WARMER TEMPERATURES VARIES
INTENSITY • The amount of ENERGY transferred by a Sound Wave is the INTENSITY of the Sound Wave. (Amplitude) • LOUDNESS is how people perceive INTENSITY. • INTENSITY is measured in DECIBELS. • Baby Crying = • 90 -115 dB • Cat Purring = • 25 dB • Airplane taking off = • 140 dB
PITCH & FREQUENCY • PITCH is the human perception of the • FREQUENCY of a Sound Wave. • FREQUENCY = the number of wavelengths per sec. • FREQUENY is measures in HERTZ (Hz). Lower Frequency Higher Frequency
Christian Doppler In 1842 – Austrian physicist Christian Doppler described what became known as the “Doppler Effect” as “A change in Pitch or Frequency that occurs when a source of a sound is moving in relation to the listener.” http://www.youtube.com/watch?v=Man9ulEYSgk&feature=related
INFRASONIC vs. ULTRASONIC • HUMANS can hear between 20 and 20,000 Hz. • DOGS and BATS have ULTRASONIC hearing – they can hear sounds “Beyond” what humans can hear. • Some things like earthquakes can make INFRASONIC, or SUBSONIC, sounds “Below” what human can hear. • ULTRASONIC waves can even be used by doctors to see inside the body.
ECHOLOCATION Some animals use sound waves to locate and catch their prey.