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Discover how a plastic or paper cup affects sound vibrations.
What You Need:
- One large paper or lightweight plastic cup (you can reuse one from a fast food restaurant)
- 2 pieces of string, each 24 inches long
- Paper clip
- Nail or pen/pencil
- Cellophane tape
- Cup covered with heavy duty plastic wrap secured with a rubber band
- Dry cereal
To Do and Observe:
1. Pinch one end of the second piece of string tightly between the thumb and first finger of one hand. Pull it through the thumb and first finger of the other hand, sliding your fingers down the string. Keep the string very tight. How would you describe the sound it makes? Try plucking this string. What type of sounds result?2. Wrap the loose end of the string attached to the Hilarious Honker around the pointer finger of one hand. Hold the cup with the other hand. Pull the string until it is tight. Pluck the string with a free finger. What do you hear? Make the string shorter, but keep the same tension on it. How does this affect the sound? Make the string less taut. How is the sound affected? Is it louder or softer than the string alone?3. Place the open end of the cup on a flat surface, like a table. Pluck the taut string. Put your ear on the table and pluck the string again. Hold the cup so the open end is pointed away from the flat surface. Compare the sounds when you pluck the string.4. Now, take your Hilarious Honker to the sink and wet the string. Hold the cup with one hand, and pull the string through the thumb and first finger of your other. Slide your finger along the string. How would you describe the sound? Try strumming the string. Why is the sound so much louder when the string is wet? When the string is dry, what occupies the tiny spaces between the fibers of string? When the string is wet, what occupies those tiny spaces?5. Make sure the plastic is tightly stretched across the second cup. Place ½ teaspoon of salt on the plastic. Aim the Honker at the plastic covered surface and pluck the string. What happens? Try drawing your fingers along the string to make the Honker "sing." What happens to the salt? Replace the salt with rice and repeat. Try the other materials.
What's Going On:
How does the size or weight of the items placed on the plastic-covered cup influence the effect of the sound waves? How does the intensity (loudness) of sound affect the movement of the items on the plastic covered cup?
Help your children see the effects of sound waves generated by the Hilarious Honker. Have them rest the open end of the Honker against a glass of water while they pluck or vibrate the string. Ask them to draw a picture of the resulting waves rippling across the water's surface.