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lab_speed_of_sound_group_lab

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					Names:
Period:

                                       Speed of Sound
Objective: To determine the speed of sound using the concept of resonance.

Procedure:
1. Fill your cylinder about 3/4 full of water. Place the glass resonance tube in the cylinder.

2. Select a tuning fork and record its frequency.

3. Strike the tuning fork against one of the rubber hammers (or the heel of your shoe, your knee,
or some other soft surface). Never strike the tuning fork against a hard surface!

4. Hold the tuning fork horizontally, with its tines one above the other, about 1 cm above the
open end of the tube. Make sure that the tuning fork does not come into contact with the glass
tube, as it may shatter the glass! Starting with the tube nearly completely immersed in the water,
move both the fork and the tube upward until you find the air column length that gives the very
loudest sound (once you find the approximate location, you will want to move the tube and fork
back and forth). Make sure that the sound that you hear is the same pitch that you hear when the
fork is held next to your ear. If you hear a higher pitch instead, you have found one of the fork's
harmonics and not the fundamental mode of vibration.




5. While the tube is still in the correct position for resonance, measure the distance from the top
of the tube to the water level.

6. Measure the inner diameter of the resonance tube.

7. Correct the measured length of the resonance tube by adding 0.4 times the diameter of the tube
to the measured length of the air column.

8. Knowing that the corrected length of the air column is one fourth of the wavelength of the
sound vibrating in the air column, compute the wavelength of that sound.

9. Using the frequency and wavelength of the sound, compute the speed of sound in air.

10. Repeat steps 2 through 9 for a tuning fork having a different frequency.

11. Measure the temperature of the air in the room.

12. Knowing that the accepted value for the speed of sound in air is 332 m/s at 0 °C, and that the
speed of sound in air increases by 0.6 m/s for each °C above zero, calculate the accepted value for
the speed of sound at the temperature of the room.

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Names:
Period:

Please turn in this data sheet with your names on it, the data filled out with calculations,
and the questions answered on the other side!

Data:
Trial 1:
Frequency of tuning fork: ___________________Hz

Length of air column: ________________ cm = ___________________ m

Diameter of the resonance tube = _________________ cm = ___________________ m

Show calculation for corrected length:



Corrected Length = _______________________ m

Wavelength of the sound wave = ______________________ m

Using frequency and the wavelength of the sound, show your calculation for determining the
speed of sound in air.




Speed of sound in air = _____________________________ m/s


Trial 2:
Frequency of tuning fork: ___________________Hz

Length of air column: ________________ cm = ___________________ m

Diameter of the resonance tube = _________________ cm = ___________________ m

Show calculation for corrected length:



Corrected Length = _______________________ m

Wavelength of the sound wave = ______________________ m

Using frequency and the wavelength of the sound, show your calculation for determining the
speed of sound in air.




Speed of sound in air = _____________________________ m/s

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Names:
Period:

Room Temperature: _______________ °C

Accepted Value for Speed of Sound: ________________ m/s

Average Calculated Speed of Sound: _________________ m/s

Show work for % Error of Avg. Calculated Speed




Percent error: ________________


Interpretations – Please write out the following in complete sentences.

   1. How does your average calculated speed of sound compare with the accepted value?
      What is the percent error?




   2. Suppose the temperature in the room had suddenly increased. How would this have
      affected your recorded frequency? Your recorded air column length? Your recorded
      wavelength?




   3. How does the speed of sound depend upon the frequency of the sound? Do high-
      frequency sounds travel faster, slower, or at the same speed as low frequency sounds?




   4. List two things that caused error in your experiment. Human error and/or calculation
      error are not errors!


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posted:4/30/2011
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