A man is standing between two vertical walls 680 m apart. He claps his hands and hears two distinct echoes after 0.9 se,conds and 1.1 second respectively. What is the speed of sound in the air?
Given : Time of first echo, `t_i = 0.9 s`
Time of second echo, `t_2 = 1.1 s`
Distance between man and wall, d = 680 m
To find : Speed of sound in air, V = ?

Explanation

Speed of sound in air, `V = (2d)/t`
`V= (2d)/(t_1 + t_2)`
`V = (2xx 680)/((0.9 + 1.1))`
`= (2 xx 680)/2`
Speed of sound in air, V = 680m/s