Calculating the Speed of Sound
Summary
In this physical science lab, students will calculate the speed of sound. They will observe that the speed of sound is constant, regardless of wavelength or frequency, and see the inverse relationship between wavelength and frequency.
CollapseLearning Goals
Learning goals and Key concepts:
Students will realize how temperature affects the speed of sound. They will obtain a better grasp of the relationship between wavelength and frequency. They will understand percent error, and it will be reinforced that a certain amount of error is acceptable (and expected) in science.
Skills: Replication of trials to increase accuracy, understanding of resonance
Vocabulary:
-Frequency
-Wavelength
-Resonance
Students will realize how temperature affects the speed of sound. They will obtain a better grasp of the relationship between wavelength and frequency. They will understand percent error, and it will be reinforced that a certain amount of error is acceptable (and expected) in science.
Skills: Replication of trials to increase accuracy, understanding of resonance
Vocabulary:
-Frequency
-Wavelength
-Resonance
Context for Use
This is an activity conducted in 9th grade physical science. During a 50 minute class period, 10 minutes are spent reviewing the material, 5 minutes are spent describing the lab, and 35 minutes are spent conducting the lab. The students should be familiar with the speed of sound equation. It is an easy activity to adapt for other settings.
Description and Teaching Materials
After introducing the material and vocabulary, the lab is conducted. Students work in groups of two.
Materials:
-Ruler
-Plastic tube (12-15 inches long) - 1.5 to 2 inches in diameter
-Coffee can filled with water
-5-7 tuning forks with different frequencies
-Data sheet
Students strike the tuning forks and place them near the opening of the tube. One end of the tube should be placed in the water. The tube is raised or lowered until a resonance is achieved. Students then measure the length of the tube that is above the water, and record this value in the "wavelength" column. The speed of sound is then calculated (with temperature being considered). The percent error is then determined. Data Sheet (Acrobat (PDF) 42kB Sep11 08)
Materials:
-Ruler
-Plastic tube (12-15 inches long) - 1.5 to 2 inches in diameter
-Coffee can filled with water
-5-7 tuning forks with different frequencies
-Data sheet
Students strike the tuning forks and place them near the opening of the tube. One end of the tube should be placed in the water. The tube is raised or lowered until a resonance is achieved. Students then measure the length of the tube that is above the water, and record this value in the "wavelength" column. The speed of sound is then calculated (with temperature being considered). The percent error is then determined. Data Sheet (Acrobat (PDF) 42kB Sep11 08)
Teaching Notes and Tips
Assessment
The lab is discussed the following day - sometimes students need to finish the calculations after class. Possible sources for error are discussed.
Standards
I. B. 1, I. B. 3, I. B. 4 - Scientific Inquiry