WAVE INTERACTIONS

Longitudinal Wave wave particles vibrate back and forth along the path that the wave travels.Compressional Wave

• CompressionsThe close together part of the wave

• Rarefactions The spread-out parts of a wave

Transverse waveswave particles vibrate in an up-and-down motion.

Transverse waves

• CrestsHighest part of a wave

• TroughsThe low points of the wave

Amplitude- is the maximum distance the particles in a wave vibrate from their rest positions.

Frequency - the number of waves produced in a given time

Waves transfer energy without transferring matter.

Frequency= waves/time

Wave VelocityWave Velocity - is the speed with which a - is the speed with which a wave crest passes by a particular point in wave crest passes by a particular point in spacespace

It is measured in meters/second.It is measured in meters/second.

Wave Velocity = Frequency Wave Velocity = Frequency Wavelength Wavelength

Speed of Sound• Medium velocity m/sec

air (20 C) 343air (0 C) 331water (25 C) 1493sea water 1533diamond 12000iron 5130copper 3560

glass 5640

II. Properties of Sound

Pitch- description of how high or lowthe sound seems to a person

. Loudness- how loud or soft a sound is perceived to be.

Loudness of Sound in DecibelsSound Loudness (dbs) Hearing

DamageAverage Home 40-50

Loud Music 90-100 After long exposure

Rock Concert 115-120 Progressive

Jet Engine 120-170 Pain

Ultrasound

- sound waves with frequencies above the normal human range of hearing. Sounds in the range from 20-100kHz

Infrasound - sounds with frequencies below the normal human range of hearing.Sounds in the 20-200 Hz range

http://www.chloetufts.com/ultrasound/index.php

Interference• the result of two or more sound• waves overlapping

Different sounds that you hear include (A) noise, (B) pure tones, and (C) musical notes.

Standing sine wave patterns of air vibrating in a closed tube. Note the node at the closed end and the antinode at the open end. Only odd multiples of the

fundamental are therefore possible.

Standing waves in these open tubes have an antinode at the open end, where air is free to vibrate.

Standing sine wave patterns of air vibrating in an open tube. Note that both ends have anitnodes. Any

whole number of multiples of the fundamental are therefore possible.

Doppler Effectis the apparent change in the frequency of a sound caused by the motion of either the listeneror the source of the sound.

Sounds from Moving Sources.Sounds from Moving Sources. A moving source of sound or a moving A moving source of sound or a moving

observer experiences an apparent shift observer experiences an apparent shift of frequency called the of frequency called the Doppler Effect.Doppler Effect.

If the source is moving as fast or faster If the source is moving as fast or faster than the speed of sound, the sound than the speed of sound, the sound waves pile up into a shock wave called a waves pile up into a shock wave called a sonic boom.sonic boom.

A sonic boom sounds very much like the A sonic boom sounds very much like the pressure wave from an explosionpressure wave from an explosion

Supersonic FlightSupersonic Flight

Resonance the frequency of sound waves exactly matches the natural frequency of an object.

Water Waves

TsunamiWave length, 500 to 600 km in ocean

Tsunami WarningTsunami Warning• On December 26, they were playing in the sea when On December 26, they were playing in the sea when

Tilly suddenly found the water was bubbling, like on Tilly suddenly found the water was bubbling, like on top of a beer. She immediately realized tsunami was top of a beer. She immediately realized tsunami was coming because the scene reminded her of a coming because the scene reminded her of a geography lesson about Hawaii's 1946 tsunami. geography lesson about Hawaii's 1946 tsunami.

• Right away, Tilly told her parents, sister and other Right away, Tilly told her parents, sister and other tourists to escape quickly, but at first they were in tourists to escape quickly, but at first they were in half belief. However, seeing Tilly's serious and firm half belief. However, seeing Tilly's serious and firm expression, people started to be convinced of the expression, people started to be convinced of the seriousness of the thing and instantly left the beach. seriousness of the thing and instantly left the beach.

• At last over 100 tourists were ended up in safety with At last over 100 tourists were ended up in safety with no deathno death

http://www.phy.ntnu.edu.tw/java/propagation/propagation.html