A boy stands 60 m 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 18 s. Calculate the speed of sound.

Explanation

Distance of boy from the wall d = 60 m
Total distance travelled by the sound = 2d = 120 m
Time interval between the `1^(st)` and `51^(st)` clap = 18 s
` therefore `Time interval between two successive claps`= (18)/(50) s`
or Time taken for the echo to be heard `t = (18)/(50) s`
Hence speed of sound ` V=("total distance travelled 2d ")/( "time taken" ) `
` or v=(120 m)/( (18 //50)s )= 333 ms ^(-1)`