Travel of Sound Through Various Phases of Matter

INTRODUCTION

To reach your ear, sound usually travels through the air. But sound can travel through other things too. Try the activity below to see how well sound travels through the different states of matter: solids, liquids, and gases.

MATERIALS

• 3 zip-closing plastic bags
• Water
• Sand or dirt
• Wooden stick or spoon

WHAT TO DO

1. Put sand or dirt in a plastic bag so that it is about half full. Push the extra air out and then seal it so that no sand or dirt will leak out. Lay the bag on its side.
2. Fill another plastic bag with water so that it is as full as the bag of dirt. Push the extra air out and then seal it so that no water will leak out. Lay the bag on its side.
3. Blow into one of your plastic bags so that it is inflated. Let some air out until the bag is as full as the bags of dirt and water. Seal it so that no air will leak out. Lay the bag on its side.
4. Clear off a table and place one of the bags on the table. Put one ear gently on the bag and put your finger in your other ear. Lightly tap or rub the table with the wooden stick from about an arm’s length away. How well can you hear the sound? Lift your ear off the bag and tap or rub the stick again. Do you hear it better with or without the bag?
5. Repeat step 4 with the other two bags.

QUESTIONS

1. Through which bag did you hear the sound best? Through which bag was the sound hardest to hear?
2. People who lived on the Great Plains in the early days of the United States put an ear on the ground to tell if buffalo or horses were coming. Why didn’t they simply listen in the air?
3. Dolphins and whales communicate through great distances underwater. Do you think they could communicate from so far away if they lived on land?

SOURCE

"The Best of Wonders Science: Elementary Science Activities." American Institute of Physics, Delmar Publishers: Albany, NY, 1997, p. 456.

© S. Olesik, WOW Project, Ohio State University, 2000.