Sound and Resonance Page 1 Sound and Resonance List of Materials Needed Sample Curriculum Sound Information

Transcription

1 Sound and Resonance Page 1 Sound and Resonance Sound Words 2 Sound and Vibrating Objects 3 Soda Bottle Symphonies 5 Hooey Stick Mystery 7 The Tacoma Narrows Bridge 9 Springs and Waves Demonstration 10 Coat Hanger Stethoscope 12 Sounding Tubes 14 Wine Glass Resonance 16 Soda Straw Symphony 18 Screaming Soda Cans 20 List of Materials Needed Sample Curriculum Sound Information

2 Sound and Resonance Page 2 Sound Words Scientific Concept Involved: Words which describe sounds often mimic those sounds. Equipment Needed: Your thinking cap. Procedure: Make a list of words for different sounds. How many can you come up with in five minutes? What do the words have in common (they should make you think of the sounds they represent). Which words best represent their sounds. Vocabulary Development: Fill in your list of words here: Data Collected: Questions: Conclusions and Comments: Further Investigations: Application to Everyday Life and Other Disciplines: Pitfalls to Avoid When Doing the Experiment: Best Grade Level: Show-Me Standards:

3 Sound and Resonance Page 3 Scientific Concept Involved: Sound and Vibrating Objects Sounds result when molecules are set into vibrational motion. This vibrational motion occurs when the molecular medium which was distorted desires to return to its original shape. This desire to return to one s original shape is called elasticity and is the characteristic which determines the velocity of sound traveling through the material. A good example of a substance desiring to return to its original shape is the tires on your car. If you look at them, you will see that they are flat on the bottom side. If you were to roll the wheel over and the flat side never returned to its original shape, the car ride would be very bouncy. However, elasticity allows the flat side to round out as soon as the stress is relieved. The distortion of a body of matter and its return to its original shape is called elasticity, and objects which are distorted and return to their original shape at regular intervals are said to vibrate. Equipment Needed: Procedure: Stick or ruler, table top. Place the ruler on the table top so that the 10 inch mark is even with the edge of the table. This means you will have a 2 inch overhang. Now lift up on the ruler s edge and quickly release the ruler. Note the pitch of the sound. Now move the ruler to the 8, the 6, and the 4 inch marks, each time flicking the ruler with one hand and holding the other hand of the ruler firmly to the table top with the other hand. Each time record the pitch of the sound. Vocabulary Development: Pitch, vibration, and elasticity. Data Collected: Questions: 1. What happens to the pitch as the length of the ruler overhang increases? 2. What do you think would be the pitch of a violin? A bass fiddle? A snare drum? A kettle drum? 3. Can you deduce the relationship between the length of a vibrating object, such a string, and the sound made by the object?

4 Sound and Resonance Page 4 Conclusions and Comments: Further Investigations: Place a thin piece of paper or grass between your thumbs, making a reed whistle. Blow between your thumbs and notice the sounds you can create. Place a piece of cellophane over your comb and placing your lips tightly on the surface, gently voice-blow across the comb s teeth. Notice the sound you create? How do your lips feel as you blow your Komb Kazoo? Place your hand on your larynx and make various humming sounds with your mouth opened, and then with your mouth closed. Notice the difference in your larynx s vibration speed in relation to high or low pitch. Application to Everyday Life and Other Disciplines: Pitfalls to Avoid When Doing the Experiment: Best Grade Level: Show-Me Standards:

5 Sound and Resonance Page 5 Scientific Concept Involved: Soda Bottle Symphonies Sound is produced when molecules are made to vibrate in a periodic pattern. The pitch of the sound depends on the length of the vibrating object. The longer the vibrating object, the lower the pitch. Equipment Needed: Glass bottles, water. Procedure: Put water in a soda bottle and blow across the top. Experiment with the sounds made when you blow across bottles containing different amounts of water. Quantify the experiment by filling different bottles with measured amounts of water (for example, 10 ml, 20 ml, 30 ml, etc.) or with water to measured heights (2 cm, 4 cm, 6 cm, etc.) and comparing the sounds. Instead of blowing across the top of the bottle, tap on the side of the bottle with a pencil, ruler, or pen. Are there any differences compared to when you blow across the top of the bottle? Vocabulary Development: Data Collected: Questions: 1. What is the relationship between the height of the water and the pitch of the sound when you blow across the top of the bottle? 2. What is the relationship between the height of the air and the pitch of the sound when you blow across the top of the bottle? 3. If we really believe that higher pitch is caused by shorter vibrating objects, as suggested in the previous experiment, what is vibrating to cause the sound when you blow across the top of the bottle?

6 Sound and Resonance Page 6 Conclusions and Comments: When you blow across the top, you cause the column of air in the bottle to vibrate up and down and produce sound. Further Investigations: Make a set of musical bottles and play a song on them. Application to Everyday Life and Other Disciplines: Pitfalls to Avoid When Doing the Experiment: The experiment where you blow across the top of the bottles produces the right result (longer length of air column produces lower pitch). Students may see the length of the water column rather than the length of the air column and get confused. The experiment where you tap on the bottles produces the wrong result. Of course, the result really isn t wrong, it just isn t easy to explain. I did this once with fourth graders, and I was very surprised to find they did not know the difference between pitch of sound (high or low) and volume of sound (loud or soft). Best Grade Level: Show-Me Standards:

7 Sound and Resonance Page 7 Scientific Concept Involved: Hooey Stick Mystery Vibrations can be created using many methods. You can pluck the string of a musical instrument and cause it to vibrate. You can pound with a stick on a drum set and cause the drum membrane to vibrate. You can drive your car over a cattle grate and feel the car vibrate. Vibrations result when a repetitive movement in equal time sequences is sustained. You will notice that the hooey stick contains many equally spaced notches. If you can consistently rub another stick over these notches, a sustained vibration will be maintained. The rate of vibration can be changed by the rate at which the moving stick bumps along the hooey stick. Also the freedom of the hooey stick to vibrate can be changed by the tension of your hold on the hooey stick.. Equipment Needed: Procedure: Hooey stick, dowel stick, patience. Hold the hooey stick in one hand and the dowel stick in the other. Rub the dowel stick along the notched portion of the hooey stick. You may have to rub slower or faster and grip the hooey stick with more or less pressure. When everything is right, the propeller on the hooey stick will begin to rotate. Once you get it to go one direction try to reverse the direction of the propeller by changing your method of rubbing or holding the hooey stick. Vocabulary Development: Vibration. Data Collected: Questions: 1. What is the relationship between the rate you move the dowel stick and the rate the propeller rotates? 2. What do you have to do to get the propeller to reverse direction of rotation?

8 Sound and Resonance Page 8 Conclusions and Comments: Further Investigations: Does the number of notches per inch affect the rate of rotation? Does the length of the notched region affect the rate of rotation? Application to Everyday Life and Other Disciplines: Pitfalls to Avoid When Doing the Experiment: Best Grade Level: Show-Me Standards:

9 Sound and Resonance Page 9 The Mystery of the Tacoma Narrows Bridge Scientific Concept Involved: Resonating objects can produce sound. They can also produce disasters. Equipment Needed: Tacoma Narrows Bridge video. Procedure: to us. We will watch a short video and then discuss the events we saw and what they might mean Vocabulary Development: Data Collected: Questions: Conclusions and Comments: Further Investigations: Application to Everyday Life and Other Disciplines: Pitfalls to Avoid When Doing the Experiment: Best Grade Level: Show-Me Standards:

10 Sound and Resonance Page 10 Scientific Concept Involved: Springs and Waves Demonstration Light and sound travel in waves. Light waves can travel through a vacuum while sound waves require an elastic molecular medium. Light waves travel very fast, 300,000,000 meters per second (what is that speed in scientific notation?), while sound waves travel more slowly. The speed of sound in air is only 331 meters per second at 0 C. Does anybody know how fast sound travels in a vacuum? Light waves slow down when they travel through media more dense than a vacuum. For example, the speed of light in water is about 133,000,000 meters per second and in glass is about 152,000,000 meters per second. The speed of sound, on the other hand, depends on the elasticity of the molecular medium. In a vacuum, sound has a speed of zero (that answers the question in the paragraph above), in air sound has a speed of about 330 meters per second, and in water sound travels about 1,435 meters per second. In oak, sound travels about 3,850 meters per second and in aluminum, about 5,104 meters per second. Light waves, which are a form of electromagnetic waves, are examples of transverse waves, and sound waves are examples of longitudinal or compressional waves. We will see what these terms mean during this activity. Equipment Needed: Two types of springs, each made of a different type of steel, and one wave catcher. Procedure: 1. Have one person hold one end of the larger diameter spring, while another person pulls the spring until it is stretched about 10 feet (depending on the length of the spring). The second person now moves the spring back and forth. One back and forth motion is called a pulse or a vibration. Observe the motion of the coils of the spring. Increase the rate of vibrations and again observe the results. 2. Now try to catch a wave compression, called a crest. 3. Next try to catch a wave rarefaction, called a trough.

11 Sound and Resonance Page We will now look at a different type of wave, called a transverse wave. It has some of the properties of light. This wave can be created by having the person making the wave move his hand from side to side. Observe and record the new wave design. 5. Use the smaller diameter spring and record any differences in this wave s velocity (and other properties) compared to the large spring s velocity. Vocabulary Development: Transverse wave, longitudinal wave, frequency, period, reflection, energy, compression, rarefaction, and velocity. Data Collected: Questions: 1. As you increased the rate of vibration, did you have to increase the amount of energy you put into the system? Which would have more energy, a red light wave or a violet light wave? Which would have more energy, a low pitch musical note or a high one? 2. When you captured the compression portion of a sound wave, how many coils did you capture? When you captured the rarefaction portion of the sound wave, how many coils did you capture? Do you think the number of air molecules in the compression portion of a sound wave would be high or low compared to the rarefaction portion? Do you think the compression portion would have high or low pressure? Conclusions and Comments: Further Investigations: Application to Everyday Life and Other Disciplines: Pitfalls to Avoid When Doing the Experiment: Best Grade Level: Show-Me Standards:

12 Sound and Resonance Page 12 Scientific Concept Involved: Coat Hanger Stethoscope The ability of sound to travel through different materials depends on the elasticity of the material. Elasticity is the desire of a substance when distorted to go back to its original shape. The greater the elasticity of a substance, the greater the velocity of the sound waves traveling through this material. Equipment Needed: Coat hanger, string, two cups, rocks, water, air, solid pieces of wood, metal, and a good ear for sound. Procedure: 1. Tap your desk with your knuckles and listen for the sound. Next place one ear on the desk and again tap the desk and listen for the sound. 2. If you have an aquarium in the room, tap two rocks together under the water and listen for the sound. Next place one ear on the glass and again listen for the sound of the rocks hitting together. 3. Make a simple stethoscope by first cutting a 4 foot piece of string. Next, punch a small hole in the bottom of a cup and push one end of the string through the hole. Tape the string to the bottom so that it will not come out of the cup. Do the same to the other end of the string. Now holding the two cups level, cut the string in half and tie each of the new ends around the bottom wire of a coat hanger. Place the two cups over your ears and walk around the room banging your coat hanger into different objects recording the different sounds. Vocabulary Development: Sound velocity, elasticity, loudness. Data Collected:

13 Sound and Resonance Page 13 Questions: 1. Do you think sound travels faster in air, water, or solids? 2. Why does the simple stethoscope make sounds sound louder? Conclusions and Comments: Further Investigations: Try to improve the design of your stethoscope. Application to Everyday Life and Other Disciplines: Pitfalls to Avoid When Doing the Experiment: Best Grade Level: Show-Me Standards:

14 Sound and Resonance Page 14 Scientific Concept Involved: Sounding Tubes If pipes and tubes of the proper length are open at both ends, they can create and amplify sound waves. The length of a tube open at both ends must be a multiple of half the wavelength of the sound being produced. Equipment Needed: Corrugated plastic tube approximately 1.5 inches in diameter and some small pieces of paper. Procedure: Grab one end of the tube and begin swinging the tube around your head, slowly at first and then faster. Make a note of changes in loudness and pitch. Now place some small pieces of paper on a table or chair or your hand and again swing the tube around your head. Make a note of what happens to the pieces of paper when the still end of the tube is placed over them. Vocabulary Development: Pitch, loudness, and frequency. Data Collected:

15 Sound and Resonance Page 15 Questions: 1. Does the velocity of your swing make a difference? 2. What happened to the pieces of paper when the still end of the swinging tube was placed over them? Why? 3. What type of musical instrument does the tube resemble? Conclusions and Comments: Further Investigations: Does the length of the plastic tube make a difference? Does the diameter of the plastic tube make a difference? Application to Everyday Life and Other Disciplines: Pitfalls to Avoid When Doing the Experiment: Best Grade Level: Show-Me Standards:

16 Sound and Resonance Page 16 Scientific Concept Involved: Wine Glass Sound Resonance Many musical instruments obtain loudness by having a string or reed cause a pipe or wooden box to resonate. Resonance results when two objects have the same natural frequency of vibration. You may have noticed that when a truck or plane goes by your home, some things in your houses begin to vibrate on the shelves. This is an example of resonance. When you pluck a guitar string, it vibrates, but so does the entire box of the guitar. When the box vibrates, more air is set into motion and the sound produced by the guitar is much louder. Equipment Needed: Glass or wine goblet, some water, wet finger, and some patience. Procedure: Put some water in the glass, wet your index finger, and place it on the edge of the glass. Now begin to move your finger around the edge of the glass, exerting light pressure until you get a sound. Vocabulary Development: Resonance Data Collected: Questions: 1. What do you think is causing the glass to vibrate? 2. Does the velocity of your finger make a difference in the pitch? 3. Do you find that there is a certain optimum velocity of your finger necessary to get the maximum sound?

17 Sound and Resonance Page 17 Conclusions and Comments: Further Investigations: Does the shape of the glass make a difference? Does the amount of water in the glass make a difference? Application to Everyday Life and Other Disciplines: Pitfalls to Avoid When Doing the Experiment: Best Grade Level: Show-Me Standards:

18 Sound and Resonance Page 18 Scientific Concept Involved: Soda Straw Symphony The air in a pipe can resonate if the pipe is of the proper length. If the pipe is open at both ends, it will resonate if the tube length is equal to ½, 1, 1 ½, etc. wavelengths of the sound wave; if the tube is closed at one end, it will resonate if the tube length is ¼, ¾, 1 ¼, etc. the wavelength of the sound wave. The air in a column in a tube can be set into motion by using a variety of methods. Some instruments like the saxophone, clarinet, and bassoon use a reed. Others like the trumpet and trombone use the musician s lips. Still others like the flute, piccolo, and organ blow air across a sharp edge. Equipment Needed: Scissors, straws, a good ear, a classroom with a door you can close, and a patient principal. Procedure: 1. Flatten one end of a straw back about one inch from the end. 2. Snip the flat end from the center to the sides to form two flat triangles about ¼ to ½ inch long.. 3. Place the flat end in your mouth and blow. If your tongue or mouth parts touch the triangular ends when you are blowing, you will get no sounc. 4. Snip various sections from your straw while you are bolowing on it and notice the different sounds you can create. 5. See if you and a partner can create the various sounds in the musical scale by cutting a number of straws to the proper lengths. Vocabulary Development: Vibration, pitch, musical scale.

19 Sound and Resonance Page 19 Data Collected: Questions: 1. What length straw is associated with a high pitch? 2. What role does the snipped end of the straw play. 3. What instrument in a band might use this design for creating sounds? Conclusions and Comments: Further Investigations: Examine a clarinet, trombone, and flute in your school band room. Which resembles your soda straw horn? Make a soda straw band using different length straws and play some tunes for the other classes in your school. Application to Everyday Life and Other Disciplines: Pitfalls to Avoid When Doing the Experiment: You may hear from your parents after this one! Best Grade Level: Show-Me Standards:

20 Sound and Resonance Page 20 Screaming Soda Cans Scientific Concept Involved: Another way to get columns of air vibrating. Equipment Needed: Two empty soda cans, maybe some ear plugs. Procedure: Hold a soda can in each hand. Hold them as loosely as you can. Bring them together until they are side by side a few millimeters apart. Blow a strong steady breath between them. Data Collected: Vocabulary Development: Questions: 1. Did you feel anything interesting about the cans as you were blowing between them? If you did, we will explain it in another experiment later this week. Conclusions and Comments: Further Investigations: Application to Everyday Life and Other Disciplines: Pitfalls to Avoid When Doing the Experiment: Close the door first! Best Grade Level: Show-Me Standards:

21 Sound and Resonance Page 21 Materials Needed stick or ruler table top. glass bottles water. hooey stick dowel stick, Tacoma Narrows Bridge video two types of springs, each made of a different type of steel wave catcher coat hanger string two styrofoam cups rocks solid pieces of wood and metal, corrugated plastic tube approximately 1.5 inches in diameter small pieces of paper glass or wine goblet scissors straws empty soda cans K: Name the five senses. Sample Curriculum First: Identify the five senses and their use; describe the sources of sound in an environment. Sixth: Identify the variables that affect pitch of vibrating objects.

22 Sound and Resonance Page 22 Here is Some Sound Information Sound and light energy is transmitted from one point to another by means of wave action. Here is a schematic representing a sound wave and how to visualize its wave nature. Here is a comparison of sound and light waves: Sound The velocity of sound in air at 0 C is 331 m/s. Sound requires an elastic molecular medium to travel through, and the velocity increases with an increase in the medium s elasticity. Is a compressional (longitudinal) wave. The human ear can detect from 20 to 20,000 Hertz. (A Hertz, abbreviated Hz, is a cycle per second.) Light The velocity of light in a vacuum is 3x10 8 m/s. Light slows down as it travels through more dense molecular media. Is a transverse wave. The human eye can detect the colors ROYGBIV.

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