Question

A boy yells in a narrow valley. The sound reflects off of a boulder that is 80 m away. How long will it take to hear the echo if
the speed of a sound wave is 320 m/s?
(speed = distance
time )
0.25 seconds
0.50 seconds
2.0 seconds
4. lubeconds

Answer 1

Answer:4 lubeconds (speed=distance over time)

Answer 2

Answer:

Time taken, t = 0.5 seconds

Explanation:

It is given that,

Speed of sound wave, v = 320 m/s

The sound reflects off of a boulder that is 80 m away.

Let t is the time taken to hear the echo. The distance covered by the sound to hear the echo is, 2d. So,

$v=\dfrac{2d}{t}$

$t=\dfrac{2d}{v}$  

$t=\dfrac{2\times 80\ m}{320\ m/s}$

t = 0.5 seconds

So, the time taken to hear the echo is 0.5 seconds. Hence, this is the required solution.