ABSTRACT

The experiment centers on velocity of sound. Three activities were conducted in this experiment. In the first and second activity, the speed of sound was determined using the resonating air column and the vernier microphone. While in the third activity, the velocity of sound in a solid was determined using a vibrating rod.

METHODOLOGY

Activity 1: Resonating Air Column

The experiment was started with the water near the top of the resonance tube apparatus. A tuning for was struck with the rubber mallet. The vibrating tuning fork was placed over the top of the glass tube. The water vessel was lowered slowly until the loudest sound was heard. The point where the sound was heard was marked. It was assured that the fork was vibrating as the vessel was lowered. If not, the fork was struck again. The distance between this point and the top of the glass tube was measured. This was recorded was L. The diameter (D) of the resonance tube was measured. The wavelength (λ) of sound produced was computed. Two more trials were made the average wavelength was determined. Using the average wavelength and the frequency engraved in the tuning fork, the velocity of the sound in air inside the glass tube was computed using the formula. The temperature (t) in degrees Celsius of air inside the glass tube was determined. It was assured that the thermometer was not touching the water. The speed of sound in air at that temperature was computed. The speed in step 10 was compared with speed in step 8 by computing for the % error. The speed obtained in step 10 was used as the accepted value. The procedure was repeated for the other tuning forks. The data and observation was recorded in Data and Results table in the succeeding page.

Activity 2: Speed of Sound

Vernier microphone was connected to Channel 1 of the interface. This microphone was positioned near the open end of a closed tube. The file “24 Speed of Sound” was opened in Physics with Computer File. As soon as the date collection began, fingers were snapped or hands were clapped near the tube. From the graph that was shown on the computer screen, the time interval between the start of the first vibration and the start of the echo vibration was determined. It is noted that this time interval is the time for sound to travel through the tube and back. The speed of sound was computed by dividing the length of the tube by ½ of the time interval obtained in step 5. The % error was computed with the same accepted value used in activity 1.

Activity 3: Speed of Sound in Solid

A thin layer of cork dust was placed as uniformly as possible inside the Kundt’s tube. The rod was clamped at its center. The rod was rubbed with a piece of cloth with coarse powder. A standing wave pattern was formed in the cork dust inside the glass tube. The distances between two consecutive displacement nodes were measured. The average of these distances was obtained. The frequency of

sound produced was determined. Using this frequency, the speed of sound (VR) in the rod was determined. The theoretical speed of sound in the rod was computed. The % error was also computed.