Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.

Vegeta
Lv 4
Vegeta asked in Science & MathematicsPhysics · 8 years ago

fundamental frequency question, 10 pts!?

A pipe open only at one end has a fundamental frequency of 256 Hz. A 2nd pipe, initially identical to the 1st pipe, is shortened by cutting off a portion of the open end. Now, when both pipes vibrate at their fundamental frequencies, a beat frequency of 12 Hz is heard. How many cm were cut off the end of the 2nd pipe?? The speed of sound is 343 m/s

tried and tried but couldnt figure it out, help pleease :D!

1 Answer

Relevance
  • 8 years ago
    Favorite Answer

    v = fλ, so λ = v/f, so 256Hz corresponds to a wavelength λ = 343/256 = 1.34m

    If L is the length of the first pipe L = λ/4 (see link)

    L= 1.34/4 = 0.335m

    The shortened pipe (length L') will have a higher fundamental frequency = 256 +12 = 268Hz

    This give a new wavelength λ' = 343/268 = 1.28m

    L' = 1.28/4 = 0.32m

    So the length cut off = 0.335 - 0.32 = 0.015m = 1.5cm

Still have questions? Get your answers by asking now.