Physics of Sound Investigation 1, Part 3

1. Sound and Vibrations Physics of SoundInvestigation 1, Part 3

2. Materials • Student Sheet no. 4 called The Tuning Fork • Student Sheet no. 5 called The Long Gong • Cord with bead • Wood blocks • Tone generator • Beans • 9-V Battery • Meter tape • Nail • Pliers with wire cutters • Scissors • Tape • Plastic cups with a hole in bottom per pair • plastic cup full of water per pair • Ping-pong ball per pair • Thread (30 cm) • Paper towel • Tuning fork per pair • Wire coat hanger • String (40 cm) • “Animal Babble and your Source and Receiver” from story book

3. Before Class Set Up Door Fiddler (for teacher) • Slide cord under the door and pull until the bead is snug behind the door. • Loop the cord over the top of the door. • While pulling down on the cord behind the door, slide the loose end under the door again. • Make as tight as possible. • Wrap the remaining length of cord tightly around the door knob 2 or 3 times. • Use slit knot to tie off. • Slide a wood block flat under the strings below the know, and stand it up. • Page 22 Picture

4. Before Class Set UpLong Gong (for teacher) • Cut string 40 cm long. • Poke a hole in the bottom of a cup with a nail, run one end of the string through the hole, and tie a knot. • Tie the loose end of the string to the center of the bent hanger. • Place long gong in plastic bag.

5. Door Fiddler • Pluck the longest string. • What do you hear? • What do you see? • How does the string feel when it is making its sound? • Pluck the shortest string. • How are these sound different? • Move wood block and pluck top and bottom of string. • What happened? • The back and forth movement of the string is called a vibration. Sometimes vibrations are so fast that they are easier to feel than they are to see.

6. Tone Generator • Place beans on speaker • Adjust the pitch and volume • What do you hear? • What do you see? • How does the speaker feel when it is making its sound? • The back and forth movement of the speaker is called a vibration. Sometimes vibrations are so fast that they are easier to feel than they are to see.

7. Tuning Fork • Demonstrate how to hold the tuning fork by the stem • Strike the wood block or the sole of your shoe • Gently strike it once • Hold it firmly • Bring the fork near your ear and listen • 3 minutes to explore • What did you hear? • What did you see when the instrument made a sound?

8. Long Gong • Place cup over one ear • Lean forward so string hang freely • Use the pencil to gently strike the wire, string, or cup once • Listen • 3 minutes to explore • What did you hear? • What did you see when the instrument made a sound?

9. Pass out The Tuning Fork sheet

10. Pass out The Long Gong sheet

11. Listening Activity • Close eyes, be very quiet, and listen carefully. • After 1 minute, identify sounds heard

12. Sound Source • Sound comes from a sound source. • A sound source is where a vibration starts. • Usually a sound source is a vibrating object, like a tuning fork and speaker. • What are some examples of sound source? (whistle, teakettle, voice)

13. Sound Receiver • In order for a sound source to be heard, it must be detected by a sound receiver. • A sound receiver is something that responds to vibrations generated by a sound source. • Our ears are our sound receivers. • Name other sound receivers. (telephone mouthpiece, microphone, animal ear)

14. Discussion • On the tone generator, what is the sound source? • (speaker) • What is the sound receiver? • (ear) • How does the sound change? • (louder or softer) • What happens to the vibration when the sound is louder or softer? • (Vibrations are stronger when the sound is louder. Vibrations are weaker when the sound is softer.)

15. More Discussion • Where have you felt vibrations and what sounds did you hear? • (musical instruments, bells, drums) • What causes sound? • (vibrations) • What is volume? • (how loud a sound is) • Read “Animal Babble and your Source and Receiver”

16. The End!!!