The minimum distance of the reflector from the listener to hear the echo of monosyllabe sound is nearly equal to :

Options

A. 16.5 m
B. 33 m
C. 66 m
D. 330 m

Answer

B

Explanation

A man can speak 5 syllable in 1 sec.
`therefore ` time to speak 1 syllable = `(1)/(5) `sec
Now, If d is the distance of reflector
` (2 d)/(v) = t `
`d = (vt)/(2) = (v)/(2) xx (1)/(5) = (300)/(10)`
` d = 33 m `
Hence the corret choice is (b).