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Sound vibes: how sound travels through different materials.

THINK: Sound is energy that travels in waves. Even though we can't see sound waves, we know that they exist. How do we know?

PREDICT: Sound needs the vibration of molecules to travel. Molecules are arranged differently in solids, liquids, and gases--the states of matter. Molecules are packed tightly together in solids, are more widely spaced in liquids, and are much farther apart in gases. How does the arrangement of molecules in different states of matter affect the movement of sound?

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You'll Need

* 1 turning for per group

* Paper and pencil

Procedure:

[] 1. Divide into groups of four to five students.

[] 2. Gently strike the tuning fork against your desk or tabletop. Then hold it a few inches away from your ear. Record your observations.

[] 3. Hold the tuning fork upside down between your thumb and index finger, with the prongs pointing downward.

[] 4. Strike the tuning fork again. While still holding the fork upside-down, touch the tip of the handle to your lower jaw, just under your chin. Record your observations.

[] 5. Pass the tuning fork around so each group member can complete the procedure.

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Conclusions

1. What state of matter was the sound traveling through when you held the tuning fork to your jaw?

2. How did the sound seem to change when you moved from holding the tuning fork in the air to holding it up to your jaw?

3. What might explain this difference?

Conclusions: 1. The sound traveled through a solid after you touched the tuning fork to your jaw.

2. The sound could be heard louder and clearer after the tuning fork touched your jaw compared to listening through the air.

3. This difference can be explained by the way sound moves more efficiently through solids than through gases like air. That's because the molecules in solids are packed more closely together so they conduct vibrations more easily.

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Title Annotation:hands-on
Publication:SuperScience
Article Type:Brief article
Geographic Code:1USA
Date:Mar 1, 2010
Words:322
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