Question

Sound waves travel at the rate of 343 m/s at 20°C. If a man standing 450 meters away from the wall of a canyon yells, “Hello,” how long will it take for him to hear his own voice echo off of the wall?

Answer 1

Answer:

2.62seconds

Explanation:

Speed is defined as the ratio of the distance covered by a body with respect to time.

Speed v = Distance (s)/Time (t)

For a traveling sound wave, the distance between the source of a sound and the reflector is '2S'.

Speed v = 2 × distance (S)/Time (T)

V = 2S/t

2S = vt

Given speed of the wave = 342m/s

Distance covered = 450m

t = 2S/v

t = (2×450)/343

t = 900/343

t = 2.62seconds

It will take him 2.62seconds for him to hear his own voice echo off of the wall.

Answer 2

Answer:

$\Delta t = 2.624\,s$

Explanation:

Sound is a form of mechanic wave, which needs a medium to propagate itself and has a constant speed. The time needed to hear his echo is:

$\Delta t = \frac{900\,m}{343\,\frac{m}{s} }$

$\Delta t = 2.624\,s$