Question

Two persons P and Q are standing at a distance of 100 m from a high wall as shown in the figure. When P gives a clap, the time interval between the two (direct and reflected) sounds heard by Q is 0.2 s . If the speed of sound is $340m{s}^{-1},$ then the distance d between P and Q is:

• A. 160 m
• B. 260 m
• C. 132 m
• D. 320 m

Answer 1

Answer: (C)

132 m

$\begin{array}{c}\frac{2\times 100}{V}-\frac{d}{V}=0.2\\ \Rightarrow \frac{200-d}{340}=0.2\\ \Rightarrow 200-d=68\\ \therefore d=200-68=132\end{array}$

$\therefore$ Option $C$ is correct.