Physics of Sound Investigation 2, Lesson 2

1. Physics of SoundInvestigation 2, Lesson 2 Length and Pitch

2. MATERIALS • Student Sheet no. 6 called the Waterphone • Student Sheet no. 7 called the Xylophone • Student Sheet no. 8 called the Kalimba • Student Sheet no. 9 called the String Beam • Large plastic bags • Meter tape • Scissors • Door fiddle (cord with bead with wood block) • 5 identical glass soda bottles with caps 12 oz • Mallet • Water • 5 xylophone tubes • Foam piece • Kalimba base • 5 flat steel springs • Craft sticks • Half meter stick with notch at end • Half of a craft stick • Fishing line about 125 cm • Binder clip • Paper cup

3. Kalimba (for teacher) • Loosen the wing nuts • Slide the 5 steel springs under the dowel • Adjust the springs so each is different length • Tighten the wing nuts • Play with thumbs or craft sticks

4. Waterphone (for teacher) • Fill 5 12 oz glass bottles with varying amounts of water • Bottle with least amount of water should contain at least 3 cm of water • Tap under the water line of the bottles to determine whether they produce pitches that are recognizably different • When tuned, screw on caps. • Put a mallet with them.

5. Xylophone (for teacher) • Picture • Place 5 different lengths of aluminum tube in foam piece • Need a mallet

6. String Beam (for teacher) • Tie a knot in the end of a 125 cm piece of fishing line • Slip the line into the slit cut into the 50 cm end of the half meter stick • Pull the knot up against the stick on the back • Poke 2 small holes in a paper cup near the base • Run the line through the cup • Run the line the length of the stick, around the end, and up the back of the stick. • Thread the line back through the slit. • Pull the line tight. • Put the binder clip over the end o the stick to hold the line. • Use scissors to cut a craft stick in half. • Insert the craft stick as a bridge between the fishing line and the 0ther end of the half meter stick. (This will increase the tension.)

7. 4 New Sound Instruments • Waterphone • Strike the bottle with mallet below the water level to produce the best sound. • Xylophone • This is a musical instrument made from a set of bars or tubes that make sounds with different pitches. • Kalimba • An African thumb piano. • Demonstrate how to insert, adjust, and play the steel springs. • String Beam • Caution: Do not remove the binder clip. • Show how to hold the cup with one hand and pluck the string with the other. • May need to get close because it is not very loud.

8. Rules for exploration time • Around 5 minutes to explore each instrument • Strike the xylophone tubes or bottles gently • Treat the instruments with care • Will rotate instruments • Make sure everyone in your group gets a turn. • Record observations make in notebook.

13. Discussion • Discuss observations. • Discuss how long the object made the sound or the length of the sound source. • Discuss the pitch of its sound. • Discuss the frequency of the vibrations. (A low frequency vibration makes a low pitched sound. A high frequency vibration makes a high pitched sound.)

14. Review • Kalimba – African thumb instrument • Xylophone – musical instrument made from a set of bars or tubes of different lengths • What happens to the pitch and the vibrations when the length of the sound source change? (A long object has a low pitch and vibrates slowly. A short object has a high pitch and vibrates quickly.) • What are some musical instruments that make different pitches by changing the length of the sound source? (trombone, flute, recorder, harp) • Science Story – Making Waves and Sound Off

15. The End!!!