The Longitudinal Displacement of a Mass Element in a Medium

question 29

Multiple Choice

The longitudinal displacement of a mass element in a medium as a sound wave passes through it is given by s = s_m cos (kx - ωt) .Consider a sound wave of frequency 440 Hz and wavelength 0.75m.If s_m = 12 µm, how long does it take an element of air to move from a displacement of 12 µm to a displacement of 0 µm?

• A)0.57 ms
• B)1.1 ms
• C)2.3 ms
• D)3.4 ms
• E)4.6 ms

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