## MCAT Question A Day - 2/17/14 - Answer!

**The speed of sound in air at a given temperature is 360 m/s. What is the shortest closed-end pipe that will produce an air column length that can resonate at a frequency of 450 Hz?**

**A.**20 cm

**B.**80 cm

**C.**90 cm

**D.**125 cm

*The correct answer is (A). The shortest pipe length will be associated with the wavelength for the fundamental tone. For a closed-end pipe, this is: wavelength = 4L. The wavelength is the ratio of the speed to the frequency: wavelength = velocity/frequency. Therefore, the shortest length is:*

*L = velocity / (4*frequency) = (360 m/s) / (4*450/s) = 0.20 m = 20 cm*

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