Question

The speed of longitudinal waves, called P waves, is 7274.0 m/s. Transverse waves, called S waves, travel at a slower 3803.0 m/s. A seismograph records the two waves from a distant earthquake. If the S wave arrives 4.47 min after the P wave, how far away was the earthquake?

Answer 1

4.47 min * 60 s/min = 268.2 s.

P-wave time = t sec.
S-wave time = (t + 268.2) s.

d(p) = d(s),
7274 m/s * t = 3803 m/s (t + 268.2),
7274t = 3803t + 1019964.6,
7274t - 3803t = 1019964.6,
3431t = 1019964.6,
t = 1019964.6 / 3471 = 293.9 s.

d = r*t = 7274 * 293.9 = 2137828.6 m
= 1336 Miles.