Lab # 8
Name:
Joseph Apap
Class:
PHY101-14995
Date:
07/11/2015
Purpose:
To be able to discuss the sound wave properties of frequency, pitch, amplitude and loudness.
To be able to discuss how the length of a sound wave affects pitch.
To be able to explain the use of controlled variables in an experiment.
Procedures:
Required Materials:
Meter Stick
2 Cardboard tubes
Scissors
Rubber bands
Wax paper
Transparent tape
Flashlight
Balloon
Small Mirror
1. Hold 1 end of a meter stick down on a tabletop with 20 cm of the stick extending past the edge of the table.
2. Pluck the end of the meter stick extending beyond the end of the table to produce vibration and sound.
3. Observe the vibration and sound created and record your observations. …show more content…
4. Repeat steps 1-3 with the meter stick extending 40 cm from the end of the table and again with 60 cm extending from the end of the table.
5. Take 1 cardboard tube and make a kazoo by cutting a hole in the center of the tube approximately 1 cm in diameter.
6.
Secure a piece of wax paper over one end of the cardboard tube with a rubber band
7. Repeat steps 5&6 with a cardboard tube approximately 10 cm shorter than the first.
8. Hum into each of the kazoos created attempting to make the humming noise as consistent as possible.
9. Cut the neck of off the balloon and tightly secure it to the end of the longer kazoo with a rubber band.
10. Attach a small mirror to the balloon at the end of the tube with a piece of transparent tape.
11. Have an assistant shine the flashlight on the mirror so that a spot of light is reflected off the mirror and onto the wall.
12. Observe how the light moves as you hum into the kazoo.
13. Keeping the angle and position of the kazoo and mirror consistent hum at a higher pitch but with the same loudness and observe how the spot of light differs from step 12.
14. Finally while keeping pitch constant, vary the loudness of the humming.
Results and evaluation of data:
The frequency of the meter sticks vibration decreased as the length it extended from the table increased. When the meter stick was plucked it produced a sound. The pitch of the sound produced decreased with the decrease in the frequency of the meter sticks vibrations as the length it extended from the table increased ( the pitch of the meter stick extending 40 cm was lower in pitch and frequency then the meter stick extending 20 cm and the meter stick extending 60 cm produced a sound with a lower pitch and had a lower frequency than both …show more content…
the meter stick extending 40 cm and 20 cm).
The longer kazoo produced a sound lower in pitch than the shorter kazoo, similar to what was observed with the meter stick.
In the experiment with the mirror reflecting light on the wall, when humming into the kazoo with a higher pitch a higher frequency of vibration of the balloon was observed. When the volume of the humming increased it so did the amplitude of the vibration of the light reflected from the mirror.
Conclusions: The purpose of this experiment was to analyze the behavior of longitudinal waves.
We accomplished this by observing sound waves and their properties:, frequency (speed of vibrations of the sound wave), amplitude, pitch (frequency of the sound as it is perceived by the listener), and loudness ( the physical response of the listener to the intensity of the sound wave).
The results of the experiment where consistent with expectations. The length of both the meter stick and the kazoo affected pitch the same way, the longer yard stick produced a lower pitch as did the longer kazoo. The higher pitch created a faster frequency of vibrations in the balloon and the louder sound caused the balloon to vibrate at higher amplitude.
The experiment successfully met its objectives by qualitatively analyzing sound waves. Using equipment to qualitatively analyze the properties of sound waves would have provided a more direct comparison of the variables manipulated in the experiment. It is also important to illustrate that when comparing changes in results it is vital to keep the other variables constant. For example , when we where observing for changes in the waves generated due to changes in pitch we need to keep the volume constant to ensure we are only observing the effects of
pitch.
References:
Hewitt, P.G. (2009). Conceptual Physics (Custom ed.). Pearson Custom Publishing.