See and hear how sound waves travel through different types of materials. Extend the experiment online and learn how you can "see" with sound waves using ultrasound.
What You Need:
- Three glasses, jars or cups of the same size
- Water (to fill one of the glasses)
- Ice cubes (to fill another glass)
- Stethoscope (optional)
- Slinky or a spring
To Do and Observe:
1. Fill one of the glasses with water
2. Fill another glass with ice
3. Leave one glass empty
4. Tap the empty glass. What sound does it make? Shake your hand while you’re tapping the glass. Can you see the vibration?
5. Now tap the glass with water. What sound does it make?
6. Tap the glass with ice. How does that sound?
7. If you have a stethoscope, listen to your heart, lungs and other muscles or organs. Do they all make sounds? What kind of sounds do they make? Why do you think you can hear them?
8. Stretch out your spring and give one end a push. Can you see the wave that travels from one end to the other? This is called a "longitudinal wave" and is how sound travels.
9. Tap the glasses again - higher sounds have faster waves and lower sounds have slower waves. Try making waves in your spring travel faster or slower to see what that looks like.
10. Explore what kind of sounds other objects make when you tap them (but don’t break anything!
What's Going On:
Sound is a vibration that travels in waves. Sound waves travel through matter - it can be a gas, like air, or a liquid, like water, or a solid, like your heart muscle. When you make a sound, the vibration moves the matter particles around it, which in turn move the next set of particles, carrying the pulse of the vibration in a wave. Sound travels in a longitudinal wave, like the spring. Tapping the glasses with different things in them demonstrates how sound waves travel differently through different materials.
Doctors and scientists use sound waves to "see" inside your body. It can be as simple as using a stethoscope to listen to your heart, or using advanced technology, like ultrasound, to create an image of your heart. Check out the online version of this Catch the Wave experiment on www.tryscience.org to learn how ultrasound works.
Encourage your child to use the internet to find out more about sound and what it can be used for. Check out sites that explore sonar, echolocation and ultrasound. Some good ones to try are: