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 $6kms^{- 1}$ and that of $P$ waves is about $9kms^{- 1}$ . 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. $54 \, km$
• B. $540 \, km$
• C. $5400 \, km$
• D. $72 \, km$

Answer 1

Answer: (C)

Let $i_{s}=$ speed of transverse wave
and $i_{p}=$ speed of longitudinal wave
$\frac{d}{i_{s}}-\frac{d}{i_{p}}=t$
$\frac{d}{6}-\frac{d}{9}=5\left(\right.60\left.\right)$
$d \, = \, 5400 \, km$