Question

A stone is dropped from the top of a cliff. The splash it makes when striking the water below is heard 3.2 s later. How high is the cliff?

2. The pressure variation is a sound wave is given by Δ P = 0.0035 sin (0.38 π x – 1350 π t) Determine a. the wavelength b. the frequency c. the speed and d. the displacement amplitude of the wave. Assume the density of the medium to be 2.2 x 103 Kg/m3

3. At a loud concert, a 120 dB sound wave travels away form a loudspeaker at 343 m/s. How much sound wave energy is contained in each 1.0 cm3 volume of air in the region near this loudspeaker?

4. A person standing a certain distance from an airplane with four equally noisy jet engines is experiencing a sound level of 140 dB. What sound level would this person experience if the captain shuts down all but one engine?

5. What would be the sound level in dB of a sound wave in air that corresponds to displacement amplitude of vibrating air molecules of 0.13 mm at 380 Hz?

6. An un fingered guitar string is 0.73 m long and is tuned to play E above middle C ( 330 Hz). A) How far from the end of the string must a fret (and your finger) be placed to play A above middle C ( 440 Hz)? B) What is the wavelength on the string of this 440 Hz wave? C) What are the frequency and wavelength of the sound wave produced in air at 25 0 C by this fingered string?

7. A) Determine the length of an open organ pipe that emits middle C (262 Hz) when the temperature is 15 0C? B) What are the wavelength and frequency of the fundamental standing wave in the tube? C) What are the wavelength and frequency in the travelling sound wave produced in the outside air?

8. A particular organ pipe can resonate at 264 Hz, 440 Hz and 616 Hz but not at any other frequencies in between. A) Show why this is an open or closed pipe. B) What is the fundamental frequency of this pipe?

9. How many beats will be heard if two identical flutes each 0.66 m long try to play middle C( 262 Hz) but one is at 5 C and the other is at 28 C?

10. A bat at rest sends out ultrasonic sound waves at 50.0 KHz and receives them returned from an object moving directly away from it at 30.0 m/s. What is the received sound frequency?

11. Two automobiles are equipped with the same single frequency horn. When one is at rest and the other is moving toward the first at 15 m/s, the driver at rest hears a beat frequency of 4.5 Hz. What is the frequency that the horns emit? Assume T = 200C

12. A factory whistle emits sound of frequency 720 Hz. When the wind velocity is 15.0 m/s from the north, what frequency will observers hear who are located at rest, A) due north B) due south C) due east and D) due west of the whistle? What frequency is heard by a cyclist heading E) north or F) west toward the whistle at 12.0 m/s. Assume T = 200C.

Answer #1

A stone is dropped from the top of a cliff. The splash it makes
when striking the water below is heard 3.9 s later. The speed of
sound in air is 343 m/s. How high is the cliff?

An unfingered guitar string is 0.71 m long and is tuned to play
E above middle C (330 Hz).
(a) How far from the end of this string must the finger be
placed to play F above middle C (349 Hz)?
m
(b) What is the wavelength on the string of this 349 Hz
wave?
m
(c) What are the frequency and wavelength of the sound wave
produced in air at 20° C by this fingered string?
Hz
m

A stone is dropped from rest into a well. The sound of the
splash is heard exactly 3.50 s later. Find the depth of the well if
the air temperature is 11.0°C.
m

An organ pipe is 5.90 m long and is closed at one end. (The
speed of sound at T = 20.0°C is v = 343 m/s.)
What is the second lowest standing wave frequency for the organ
pipe?
What is the third lowest standing wave frequency for the organ
pipe?
What is the fourth lowest standing wave frequency for the organ
pipe?
The sound level 23.2 m from a loudspeaker is 63.4 dB. What is
the rate at which sound...

3. A stone is dropped from rest into a well. The
sound of the splash is heard exactly 1.70 s later. Find the depth
of the well if the air temperature is 11.0°C.
__________ m

A stone is dropped from rest into a well. The sound of the
splash is heard exactly 2.30 s later. Find the depth of the well if
the air temperature is 12.0°C.

A stone is dropped from rest into a well. The sound of the
splash is heard exactly 3.00 s later. Find the depth of the well if
the air temperature is 16.0°C.

a) A=7, B=2
a) Consider a pipe with a length of (A+32.5) cm. If the
temperature of the air is (12.5+B) oC and the pipe is
closed in one end and open in the other, what is the frequency of
the third harmonic for the pipe? Post your answer in
hertz (Hz) and with 3 significant figures.
b) A=2, B=7
b) Consider a string with a length of (47.5 +A) cm tied at both
end (like on a stringed instrument)....

A. What length should an oboe have to produce a fundamental
frequency of 244 Hz on a day when the speed of sound is 343 m/s? It
is open at both ends.
B. What frequency is received by a person watching an oncoming
ambulance moving at 119 km/h and emitting a steady 706 Hz sound
from its siren? The speed of sound on this day is 333 m/s.
C. What energy in millijoules falls on a 0.808 cm diameter
eardrum...

Two train engines are moving in opposite directions down a close
pair of parallel tracks. Train 1 is heading south at 15.0 m/s and
Train 2 is heading north at 20.0 m/s. The engineer on Train 2
sounds a whistle with frequency 440 Hz to let the engineer on Train
1 know that he is approaching. The air temperature is 15°C.
Find the speed of sound in air at 15°C.
Sketch the scenario, and determine the frequency with which the...

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