This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn, too!
Sound is a form of energy, and is caused by something vibrating. So what is moving to make sound energy?
Molecules. Molecules are vibrating back and forth at fairly high rates of speed, creating waves. Energy moves from place to place by waves. Sound energy moves by longitudinal waves (the waves that are like a slinky). The molecules vibrate back and forth, crashing into the molecules next to them, causing them to vibrate, and so on and so forth. All sounds come from vibrations.
Materials:
- 1 tongue-depressor size popsicle stick
- Three 3″ x 1/4″ rubber bands
- 2 index cards
- 3 feet of string (or yarn)
- scissors
- tape or hot glue
Sure thing! You attach the strong to one of the ends with the index card piece on it. Here’s the experiment video for you: https://www.sciencelearningspace2.com/2009/07/harmonicas/ So happy you enjoyed the class!
My boys and I just saw the recording of the teleclass and could not see where the string was used in the harmonica experiment. Can you please explain? Otherwise we were thrilled to hear the experiment worked.Thanks
Yes, because it takes energy for the sound to travel through different mediums. 🙂
If sound is molecules vibrating and creating a domino effect with each other, then why doesn’t the sound travel on for ever and ever? Does the energy reduce?
Sound waves not only transmit through a medium, but also reflect back, depending on what the medium is made of and what the surface is like.
A noise barrier, or sound wall, is designed to reflect the noise in a different direction. They are usually made of materials that absorb sound differently than hard surfaces. Foam for example is a porous material which dampens the sound, because of all the gas pocket chambers inside the foam, and so it’s effective to dampen sound. This means that very little noise gets reflected back toward the source (or anywhere else). Streets are very reflective, so most of the noise from the highway is reflected back up to the source.
The main concept we’re having difficulty understanding is: If sound travels faster through solids than gases, why do we put up walls as sound barriers? I can hear my son much better without a wall/door between us, so it appears that sound travels faster through air.