Question

Assuming the waves travel in straight lines, how far away is the center of the earthquake?

The average speeds of transverse and longitudinal waves in rock are 8.9 km/s and 5.1 km/s respectively. A seismograph records the arrival of the transverse waves 73 s before that of the longitudinal waves.

Answer 1

Waves becoming straight is a limit problem of amplitude tending to 0 and/or the velocity of propagation (`(2pi)/(period)`) becoming 0, in the limit.

Explanation:

Waves become straight when amplitude tends to 0 and/or the

velocity of propagation (`(2pi)/(period)`) becoming 0, in the limit.

When the velocity of propagation `to`0, the period `to oo` and the

frequency `to`0.

So, in my opinion, the results for this virtual limit problem are results

for your problem.

The model is `x =h sin (kt+alpha)`, where h and/or k `to` 0.