Question

A boy stands 60m in front of a tall wall and claps. The boy continues to clap every time an echo is heard. Another boy finds that the time taken between the first and fifty first clap is 18s. The speed of sound is :

A. 333.33 m/s
B. 341 m/s
C. 370 m/s
D. 327 m/s

Answer 1

The speed of sound is calculated by dividing the distance of the echo's round trip (120m) by the time for one interval (⅔ second), resulting in about 333.33 m/s, which is option A.

Step-by-step explanation:

When the boy claps and hears the echo, the sound has to travel to the wall and back, so the total distance that sound covers is twice the distance between the boy and the wall.

If it takes 18 seconds to hear 50 echoes, then each round trip takes ½ second (because the first clap does not have a travel time).

Knowing this, we can calculate the speed of sound using the formula:

Speed = Distance ÷ Time.

The total distance for one clap's echo is 2 × 60m = 120m.

As it takes ½ second for a round trip, we do the calculation:

Speed of sound = 120m ÷ 0.5s = 240m/s.

However, since this is not one of the options, and considering the approximation of the fractions, we have to re-evaluate the time per trip.

If there were 51 claps, there are 50 intervals, and therefore, each interval is ⅔ second long (18s ÷ 50).

Then the speed of sound is 120m ÷ ⅔s = 333.33m/s, which corresponds to option A.