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How does tube length influence frequency?

What did he say?!

  • Geometry (size and shape) influences natural frequency

  • Compare how easy it is to bend a longer length of pipe versus a shorter length of pipe

  • The long pipe is easy to bend - it is "softer"

  • The short pipe is harder to bend - it is "stiffer"

Make your prediction:

Play the short and long tube to listen to the different tones.

Short Tube  (click Below)

Short Tube
00:00 / 00:05

Long Tube (click Below)

Long Tube
00:00 / 00:12

Show me!

Let me try!

Hold down the end of a 12" or 18" ruler on the edge of a table or counter.  (It works best if you press down with the palm of your hand.)  Place the ruler so about 3" is on the table.

With your other hand, press on the unsupported end and let go.  The ruler  will oscillate and you might hear a sound.

Now, move the ruler so about 6" is on the table and press with your palm.  Again, press and release the unsupported end.  What happens?  Did the ruler vibrate faster or slower when the unsupported end was shorter?

Engineers call this simple system a "cantilevered beam."

Click "Next" to see more factors that influence frequency.

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