When you start a vibration, it moves out in all directions like the ripples in a puddle. This is called a sound wave.
1. Fill the pan half way with tap water.
2. Break the toothpick into 3 or 4 pieces. Put these pieces on top of the water. Be sure they are not touching the pan or each other. They will represent water molecules.
3. Get the paper towel very wet but not dripping. When the water in the pan is still, gently squeeze the paper towel so one drop falls in the middle of the pan. You should see ripples.
Which way do the ripples go?
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Do the toothpicks move as fast as the ripples?
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4. The ripples move across the water but the toothpicks do not move with them. Just like the toothpicks, the molecules in the water do not move with the ripples. What is moving?
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When you ride a bike you use energy. When you clap your hands, you use energy, too. The harder you clap, the more energy you use. Also, the harder you clap, the louder the sound. A sound's volume is how loud or soft it is. The more energy we put into making the sound, the louder the volume.