1. Think & Solve Problems Chapter 26
April 24, 2014

2. T & S #1 Speed of Sound Waves (V): 340 m/s
Frequency of Lowest Note most people can hear (f1): 20 Hz. What is its wavelength?
What is the wavelength of a sound with a frequency (f2) of 20 KHz, the highest frequency most people can hear?

3. T & S #1 Solution Part 1 V = f ° λ λ = V / f λ = 340 / 20 = 17 meters
λ = 340/20,000
Λ = .017 meters or 1.7 cm

4. T & S #2
You have a desire to produce a sound with a wavelength (λ ) of 1 meter.
What must its frequency (f) be?
V = f ° λ
f = V/λ
= 340m/s/1m = 340 1/s or 340 Hz.

5. T & S #4
Two sounds, one at 240 Hz (f1), the second at 243 Hz (f2) occur at the same time. What beat frequency do you hear?
Fb = f2 –f1
= 243 – 240 = 3 Hz.

6. T & S #5 Two notes are sounding at the same time.
One note has a frequency (f1) of 440 Hz.
The BEAT Frequency (Fb) between the two is 5Hz.
What can the other notes frequency be?
F2 = Fb +/- F1
= or
= 445 Hz or 435 Hz

7. T & S #3 An Ocean depth Sounding Vessel is surveying the ocean floor.
The velocity of sound in this part of the ocean travels at 1530 m/s.
What is the depth of the ocean if it takes the echo 8 seconds to travel from the vessel to the ocean floor and back to the vessel?
t = 8 /2 = 4 sec for echo to travel from ocean floor back to vessel
d = v ° t = 1530 m/s ° 4 sec = 6130 meters or ~3 miles