Sunday, October 24, 2010

The Singing Glass

This is a fun and easy science experiment.  The purpose of the experiment is to show how friction can cause a glass to vibrate.


Materials:  stemmed glassware (thinner glass is better)
                 dish detergent
                 vinegar
                 small shallow bowl

Procedure:
  1. Use the dish detergent to wash the glass and your hands.  Rinse well.
  2. Place the glass on a table.
  3. Pour a thin layer of vinegar into the small bowl.
  4. Hold the base of the glass against the table with your hand.
  5. Wet the index finger of your free hand with vinegar and gently rub your wet finger around the rim of the glass.
Results:  The glass starts to sing when its rim is rubbed.

Why?  Washing the glass and your hands removes any oil that might act as a lubricant.  The vinegar dissolves any oil that might be present and increases the friction between your skin and the glass.  Rubbing your finger around the rim causes the glass to vibrate because your finger skips and pulls at the glass.  The air inside the glass is struck by the vibrating glass and begins to move back and forth in rhythm with the glass.  The pitch of the sound you hear is due to frequency (number of vibrations per second).  It's all pretty cool.

What good is posting a singing glass experiment without linking a video of C actually performing the experiment?!  Check this out:


If you are reading this via email or in a reader, you will have to click through and view the video on my blog.  Come on, you know you want to see this.  C's reaction to the singing glass makes it all worth it.  It's a short video too, less than thirty seconds.

I found this experiment in the book, Physics for Every Kid by Janice VanCleave.

I am linking this post to Science Sunday at Adventures in Mommydom.  Click on over there to find more great science experiments.

12 comments:

An Almost Unschooling Mom said...

Janice VanCleave is terrific for simple, but interesting, and clear science experiments.

Very cute video :)

Sherry said...

That looks like it would be neat! I couldn't get the video to work though :(!

Phyllis said...

That is interesting using the vinegar and soap. We just used water. My daughter was the one who could get that singing to last the longest. Did you know that Ben Franklin made a muscial instrument based on this idea? Fun stuff!

Natalie PlanetSmarty said...

It IS cool! I loved C's big eyes in the video and how he whispers at first - too funny.

Joyful Learner said...

I can't see the video from my phone but I'll have to check back later on my laptop. I love the explanations you shared and the experiment itself!

Annette W. said...

Very cool indeed!

Debbie said...

Very cool! We always used water, maybe we will try vinegar and see if we get a better affect.

MaryAnne said...

Yours worked really well! I've tried this, but I think our glasses are too thick? Maybe vinegar would work better; I've always tried water.

Unknown said...

Nice experiment. Love the video! Thank you for sharing.

Valerie @ Inner Child Fun said...

LOL Great video! C look so engrossed in it!! What a fun experiment!

Ticia said...

He is so engrossed in it! I love that!

I've never been successful at doing the singing glass trick. I'll have to try it with the soap and vinegar.

Brimful Curiosities said...

We've used wine before following a dinner party but not vinegar. Some of our wine glasses are better singers. Did you try different glasses?