Respuesta :
The given question is incomplete. The complete question is as follows-
Earthquakes produce several types of shock waves. The most well-known are the P-waves (P for primary or pressure) and the S-waves (S for secondary or shear). In the earth's crust, the P-waves travel at around 6.5 km/s while the S-waves move at about 3.5 km/s. The actual speeds vary depending on the type of material they are going through. The time delay between the arrival of these two waves at a seismic recording center tells geologists how far away the earthquake occurred. If the time delay is 73 s, how far from the seismic station did the earthquake occur?
Answer:
553.6 km
Explanation:
Given that,
speed of P-wave = 6.5 km/sec
Speed of S-wave = 3.5 km/sec
Delay time is given to be = 73 seconds
Distance is needed to find,
Since, the distance covered by P wave in 't' seconds, and S wave in "t + 73" seconds
Now, Distance = Speed × Time
⇒ Distance = Speed × (t+73 sec)
For P wave, distance is, D = Pt ...... equation (1)
and for S wave, distance is, D = S(t+73) ...... equation (2)
As, both the distances are the same, means equation (1) and (2) being equal,
Pt = S (t + 73)
Pt = St + 73 S
Pt ₋ St = 73 S
t (P ₋ S) = 73 S
t = [tex]\frac{73 S}{P - S}[/tex]
Putting this value of t in equation (1), we get,
D = Pt = [tex]\frac{73 PS}{P - S}[/tex]
Now, by substituting the values of speed of P and S waves in it, we get-
Distance = \frac{73 \times 6.5 \times 3.5 }{6.5 - 3.5}
Therefore, distance = 553.6 kilometers.
