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 = ) 0.25 seconds 0.50 seconds 2.0 seconds 4.0 seconds

Answer 1

The time it will take to hear the echo, when the speed of a sound wave is 320 m/s is 0.50 seconds.

What is the speed of sound?

Speed of sound is the rate by which the sound wave travels. The speed of sound depends on the medium by which the sound wave is travelling.

The speed of the wave can be found out using the following formula.

$s=\dfrac{d}{t}$

Here, (d) is the distance travelled by the wave and (t) is time taken by the wave to cover that distance.

A boy yells in a narrow valley. The sound reflects off of a boulder that is 80 m away.

For the echo, distance travelled will be doubled as it come back.Thus, the distance travelled by sound wave is,

$d=2\times80\\d=160\rm\; m$

The speed of sound is 320 m/s. Put these value in the above formula as,

$320=\dfrac{160}{t}\\t=0.5\rm\; s$

Thus, the time it will take to hear the echo, when the speed of a sound wave is 320 m/s is 0.50 seconds.

Learn more about the speed of sound here;

brainly.com/question/95976

Answer 2

Answer:

  0.50 seconds

Step-by-step explanation:

The time it takes for an echo to return is the time it takes for the sound to make the round trip between the source and the reflecting object.

The boulder is 80 m away from the source, so the round-trip distance is 2×80 m = 160 m. At a speed of 320 m/s, it takes sound ...

  (160 m)/(320 m/s) = 0.50 s

to make the round-trip.

It will take 0.50 seconds to hear the echo.