Question

An earthquake generates both transverse $\left(S\right)$ and longitudinal $\left(P\right)$ sound waves in the earth. The speed of $S$ waves is about $6km{s}^{-1}$ and that of $P$ waves is about $9km{s}^{-1}$ . A seismograph records $P$ and $S$ waves from an earthquake. The first $P$ wave arrives $5$ minute before the first $S$ wave. The epicenter of the earthquake is located at a distance of about -

• A. $54km$
• B. $540km$
• C. $5400km$
• D. $72km$

Answer 1

Answer: (C)

Let $i_s=$ speed of transverse wave
and $i_p=$ speed of longitudinal wave
$\frac{d}{i_s}-\frac{d}{i_p}=t$
$\frac{d}{6}-\frac{d}{9}=5(60)$
$d=5400km$