Lesson 7

Question 1

What kind of waves are sound waves?

Answer 1

Longitudinal waves

Question 2

What are the three types of sound waves?

Answer 2

~ Audible waves : sound waves which lie withing the audible range for humans
~ Infrasonic Waves: waves with a frequency that lies below the audible range for humans. Include sub-bass, elephants and other large animals echoloction techniques.
~ Ultrasonic Waves: Waves with a frequency above the audible range for humans. Include dog whistles, bats for communication, praying mantis for protection from bats

Question 3

What is bulks modules

Answer 3

~B = volume stress/volume strain
~ B = (ΔF/A)/(ΔV/Vi)
~ Volume Strain is the changing deformation
~ B = (-ΔP/ΔV)/(Vi)
~ ΔP = -B (∂s/∂x) where ∂ = partial derivative
~ ΔP = -B(∂/∂x)[Smaxcos(kx-ωt)
~ d/dx ΔP = BSmaxksin(kx-ωt) This is the periodic displacement function that causes a change in pressure
~ ΔPmax = BSmaxk when the amplitudes are related

Question 4

What is the speed in a regular transverse wave?

Answer 4

V = sqrt (T/Μ)

Question 5

Equation for the speed of sound in air

Answer 5

V = 331m/s [sqrt(1+ (Tc/273))]
Tc = air temp in Celcius
V = speed of sound in air

Question 6

What is the decibel scale

Answer 6

B = 10log(I/Io)
B = sound level in decibels
I = intensity of sound (ω/m2)
Io = threshold of human hearing 1.00 x 10^-12 ω/m2
for logaN use, a^x = N