Question

The first dancer in the line is 10 m from the speaker playing the music; the last dancer in the line is 120 m from the speaker. Approximately how much time elapses between when the sound reaches the nearest dancer and when it reaches the farthest dancer

Answer 1

Answer: 0.321 seconds

Explanation:

Let assume that air has a temperature of 20 °C. Sound speed at given temperature is $343 \frac{m}{s}$. As sound spreads at constant speed, time can be easily found by using this formula:

$\Delta t = \Delta t_{far} - \Delta t_{near}$

$\Delta t = \frac{x_{far}-x_{near}}{v_{sound,air}}$

$\Delta{t} = \frac{120 m - 10 m}{343 \frac{m}{s} }\\\\\Delta {t} = 0.321 sec$