Answer:
21828 m
Explanation:
[tex]v_{ground}[/tex] = speed of sound through ground = 6 km/s = 6000 m/s
[tex]v_{air}[/tex] = speed of sound through air = 343 m/s
t = time taken for the vibrations to arrive
t' = time taken for sound to arrive = t + 60
d = distance of the point of explosion
time taken for the vibrations to arrive is given as
[tex]t = \frac{d}{v_{ground}}[/tex] eq-1
time taken for the sound to arrive is given as
[tex]t' = \frac{d}{v_{air}}[/tex]
[tex]t + 60 = \frac{d}{v_{air}}[/tex]
using eq-1
[tex]\frac{d}{v_{ground}} + 60 = \frac{d}{v_{air}}[/tex]
[tex]\frac{d}{6000} + 60 = \frac{d}{343}[/tex]
d = 21828 m
