Question

At a country music festival, a band is playing at the end of a crowded
1947 m field when one of the players hits a note on the keyboard that has
a frequency of 400 Hz. (HINT-find the wavelength first) How many full
wavelengths are there between the stage and the last row of the crowd?

Answer 1

Answer:

2270 full wavelengths.

Explanation:

The wavelength $\lambda$ of the sound wave (assuming sound speed of  $v= 343m/s$) is

$\lambda = \dfrac{v}{f} = \dfrac{343m/s}{400hz}$

$\lambda = 0.8575m$.

Now, assuming the distance to the last row is 1947m, the number $n$ of wavelengths that fit into this distance are

$n = \dfrac{1947m}{0.8575m}$

$n= 2270.55$

which is 2270 full wavelengths.

Hence, there are 2270 full wavelengths between the stage and the last row of the crowd.