# Think & Solve Problems Chapter 26

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Think & Solve Problems Chapter 26
April 24, 2014

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?

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

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.

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.

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

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