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Ch. 17 - Waves & Sound I. Characteristics of Waves Waves Transverse waves Longitudinal waves Measuring waves

Ch. 17 - Waves & Sound I. Characteristics of Waves Waves Transverse waves Longitudinal waves Measuring waves

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Page 1: Ch. 17 - Waves & Sound I. Characteristics of Waves  Waves  Transverse waves  Longitudinal waves  Measuring waves

Ch. 17 - Waves & Sound

I. Characteristics of Waves Waves Transverse waves Longitudinal waves Measuring waves

Page 2: Ch. 17 - Waves & Sound I. Characteristics of Waves  Waves  Transverse waves  Longitudinal waves  Measuring waves

A. Waves

Wavesrhythmic disturbances that carry energy through

matter or space

Mediummaterial through which a wave transfers energysolid, liquid, gas, or combinationelectromagnetic waves don’t need a medium

(e.g. visible light)

Page 3: Ch. 17 - Waves & Sound I. Characteristics of Waves  Waves  Transverse waves  Longitudinal waves  Measuring waves

A. Mechanical Waves

Two Types:

Longitudinal Transverse

Page 4: Ch. 17 - Waves & Sound I. Characteristics of Waves  Waves  Transverse waves  Longitudinal waves  Measuring waves

B. Transverse Waves

Transverse Wavesmedium moves

perpendicular to the direction of wave motion

Page 5: Ch. 17 - Waves & Sound I. Characteristics of Waves  Waves  Transverse waves  Longitudinal waves  Measuring waves

B. Transverse Waves

Wave Anatomy

crests

troughs

wavelength

wavelength

amplitudeamplitude

corresponds to the amount of

energy carried by the wave

Page 6: Ch. 17 - Waves & Sound I. Characteristics of Waves  Waves  Transverse waves  Longitudinal waves  Measuring waves

C. Longitudinal Waves

Longitudinal Waves (a.k.a. compressional)medium moves in the same direction as wave

motion

Page 7: Ch. 17 - Waves & Sound I. Characteristics of Waves  Waves  Transverse waves  Longitudinal waves  Measuring waves

C. Longitudinal Waves

Wave Anatomy

rarefaction

compression

wavelength

wavelength

Amount of compression corresponds to amount of energy AMPLITUDE.

Page 8: Ch. 17 - Waves & Sound I. Characteristics of Waves  Waves  Transverse waves  Longitudinal waves  Measuring waves

D. Measuring Waves

Wave period

Amount of time for a full wavelength to pass a certain point

shorter wavelength shorter period

Page 9: Ch. 17 - Waves & Sound I. Characteristics of Waves  Waves  Transverse waves  Longitudinal waves  Measuring waves

D. Measuring Waves

Frequency ( f )

# of waves passing a point in 1 second

Hertz (Hz)

shorter wavelength higher frequency

1 second

Page 10: Ch. 17 - Waves & Sound I. Characteristics of Waves  Waves  Transverse waves  Longitudinal waves  Measuring waves

D. Measuring Waves

Velocity ( vw )

speed of a wave as it moves forwarddepends on wave type and medium

vw = × f vw: velocity (m/s)

: wavelength (m)

f: frequency (Hz)

Page 11: Ch. 17 - Waves & Sound I. Characteristics of Waves  Waves  Transverse waves  Longitudinal waves  Measuring waves

WORK:v = × f

v = (3.2 m)(0.60 Hz)

v = 1.92 m/s

D. Measuring Waves

EX: Find the velocity of a wave in a wave pool if its wavelength is 3.2 m and its frequency is 0.60 Hz.

GIVEN:

v = ?

= 3.2 m

f = 0.60 Hz

v

f

Page 12: Ch. 17 - Waves & Sound I. Characteristics of Waves  Waves  Transverse waves  Longitudinal waves  Measuring waves

WORK: f = v ÷

f = (5000 m/s) ÷ (417 m)

f = 12 Hz

D. Measuring Waves

EX: An earthquake produces a wave that has a wavelength of 417 m and travels at 5000 m/s. What is its frequency?

GIVEN:

= 417 m

v = 5000 m/s

f = ?

v

f