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### Sound - Physics

1. What is a wave? • A wave is a repeating disturbance that transfers energy through matter or space. • When an object vibrates it causes the particles around it to move. • These particles bump into particles close to them, transferring energy possessed. This continues until they run out of energy. Longitudinal Waves Waves transfer energy without transferring matter. Transverse Waves
2. Therefore sound can be defined as … •A form of energy caused by vibrations. This energy is transferred due to pressure through longitudinal waves. In a longitudinal wave the matter in the wave moves back and forth parallel to the direction of the wave. Sound doesn’t travel through vacuum.
3. Sound can be reflected, refracted, and absorbed and also shows evidence of interferencealso be known as echo. Reflection of sound is and diffraction. Reverberation of sound is the repeated multiple reflection of sound in any enclosed space. Reverberation occurs when the echo produced is as same/strong as the sound produced by the source. Refraction of sound occurs when the wave travels from one medium to another.
4. Wavelength Wave Speed  f Time period Wavelength () is the distance from the center of one compression to the center of the next compression. Time period (t) is the time it takes for one full wavelength to pass a certain point. Frequency (f) is waves per second. Wave Speed (s) the distance covered by a complete wave in a given time.
5. • Compressions The close together part of the wave. • Rarefactions The spread-out parts of a wave. Amplitude is the maximum distance the particles in a wave vibrate from their mean positions. Amplitude controls the volume and intensity of sound. The amplitude of a longitudinal wave is determined by the closeness of the longitudinal waves. The closer the longitudinal waves and the farther the rarefaction lines. Spring A has greater amplitude than Spring B.
6. 344 m/s in air at 20 C Speed of Sound depends on: Type of medium •travels better through liquids and solids •can’t travel through a vacuum Temperature of medium
7. Doppler Effect change in wave frequency caused by a moving wave source. moving toward you - pitch sounds higher. moving away from you - pitch sounds lower.
8. Waves interfere in one of two ways: Constructive Interference and Destructive Interference.
9.  Frequency of a sound wave is heard as pitch.  highness or lowness of a sound High Low frequency frequency = High pitch = Low pitch = = Long Free Powerpoint Templates Short wavelengt
10. Low pitch. Eg. Fox horn High Pitch. Eg. Pic Healthy humans can hear from 20 Hz to 20,000 Hz Ultrasound - sound waves with frequencies above the normal human range of hearing. Ultrasonic sounds have frequencies greater than 20000 Hz. Infrasound - sounds with frequencies below the normal human range of hearing. Infrasonic sounds have frequencies lower than 20Hz.
11. Some animals can hear sounds with frequencies greater than 20000 Hz. a) Dogs (up to 35,000 Hz) b) Bats (over 100,000 Hz c) Medical diagnosis. Medical Imaging a. Acoustics – the study of sound. b. SONAR – Sound Navigation and ranging (echolocation). c. Ultrasound imaging.
12. Different sounds that you hear include (A) noise (B) pure tones (C) musical notes or beats. A - can be considered as noise as it has no pattern. B – can be considered as a pure tone as energy is transferred in a single pattern of the wave. C - musical notes or beats as it has a pattern of
13. Beats are variations of loudness (amplitude) and pitch (frequencies) caused by interference of two sounds that slightly differ. Beats differ depending on the pattern of amplitude, pitch and caused by interference of different waves.
14. Clarinet It depends on the type of instrument. There are four types. Woodwind. String. Percussion. Brass. Flute Oboe Piccolo Wo o d wi n d s ma k e mu s i c Bassoon b y b l o wi n g o n t h e t o p o f
15. •Some of the simpler instruments are the string instruments. String instruments make sound with vibrating strings, and the pitch is modified by the thickness, tension, and length of the string. Cello Guitar Harp Violin Electric Guitar
16. Drum • Percussion instruments make music by striking, shaking or scraping them. Piano Tambourine Cymbals Xylophone Maracas
17. Brass instruments make music by buzzing lips while blowing. Trombone Trumpet Tuba French Horn
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