Saturday, 17 January 2015

Vibration = Sound!

January 14th

Today we tried a few sound experiments!

We were investigating the fact that sound is made when things move.  The movement is  called vibration, and vibrations make sound!  When vibrations are small the sound is quiet.  When something makes a big vibration the sound is loud. We also discovered that the faster an object vibrates the higher the pitch is.  The sound waves are moving faster.  We noticed that the slower an object vibrates the lower the pitch is, the sound waves are moving more slowly.

Experiment #1 ~ Elastic Band test.
We placed an elastic band between our fingers.  We plucked the elastic band to make a sound.  We could see, feel, and hear the vibration!  We tried rubber bands of different widths to see if they would make a different sound.  They did!  We also tried wrapping the elastic bands around books, our chairs,  and pencil boxes and when we plucked them they made different sounds!   Some students put several elastics together and strummed them like a guitar!  Very cool!

Experiment #2 ~ Ruler test.
We placed a ruler over the edge our our desks.  We pushed down quickly on the ruler and watched it move up and down.  We tried different lengths sticking out over the edge and noticed that the ruler vibrated and made different sounds depending on how far over the desk the ruler was hanging.  The shorter the ruler was hanging over, the higher the pitch, the faster the vibration.  The farther the ruler was hanging over, the lower the pitch, the slower the vibration was.

We also read parts of this great book from our own school library.  Simple Science Sound by Mike and Maria Gordon.

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