Lecture_28_PPT

# Lecture_28_PPT - Chapter 17 Sound Waves Categories of Sound...

This preview shows pages 1–10. Sign up to view the full content.

Chapter 17 Sound Waves

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Categories of Sound Waves z Audible waves are within the sensitivity of the human ear. Range is approximately 20 Hz to 20 kHz Audible sound
Infrasonic waves z have frequencies below the audible range (<20 Hz) z Whales, elephants, hippopotamuses, crocodiles, birds and giraffes are known to use infrasound to communicate over distances. z Naturally from tornado, surf, earthquakes, volcanoes, waterfalls, calving of icebergs, aurora, lightning.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Ultrasonic waves z have frequencies above the audible range (<20 kHz) z Bats (100kHz), Dogs, Dolphins and whales z Applications Ultrasonic Imaging Ultrasonic cleaning SONAR - navigation and ranging
Periodic Sound Waves z A longitudinal wave is propagating through a gas- filled tube z The source of the wave is an oscillating piston z The distance between two successive compressions (or rarefactions) is the wavelength

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Periodic Sound Waves z As the regions travel through the tube, any small element of the medium moves with simple harmonic motion parallel to the direction of the wave z The harmonic position function is s (x, t) = s max cos (kx – ω t)
Periodic Sound Waves z s (x, t) = s max cos (kx – ω t) z The variation in gas pressure, P = -B ds/dx = B k s max sin (kx- ω t) z B = v 2 ρ , ω =k v z P = ρ v ω s max sin (kx – ω t) = P max sin (kx – ω t) z P max = ρ v ω s max

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Periodic Sound Waves z s (x, t) = s max cos (kx – ω t) z P = P max sin (kx – ω t) z A sound wave may be considered either a displacement wave or a pressure wave
Periodic Sound Waves z P = P max sin (kx – ω t) z s (x, t) = s max cos (kx – ω t) z The pressure is a maximum when the displacement is zero, etc.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 01/28/2011 for the course PHYS 011 taught by Professor Nianlin during the Fall '08 term at HKUST.

### Page1 / 31

Lecture_28_PPT - Chapter 17 Sound Waves Categories of Sound...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online