https://www.physicsforums.com/showthread.php?t=160610 Continuing off this problem.. My teacher wrote the solution on the board (and conveniently went to the hospital before our period). Problem again.. 1. The problem statement, all variables and given/known data The velocity of the transverse waves produced by an earthquake is 8.9km/s while that of the longitudinal waves is 5.1km/s. A seismograph records the arrival of the transverse waves 73s before that of the longitudinal waves. How far away was the earthquakes? 3. The attempt at a solution Doc Al's formula was.. the distance/displacement of transverse velocity is equal to the distance/displacement of longitudinal velocity * time + 73s.. Or.. d=vt=(8.9km/s)* T=(5.1km/s) * (T+73s) And eventually, the T will get isolated.. ================================ On the board.. His formula was Timetransverse=[VlongitudinalΔt]/(vtransverse-Vlongitudinal) Δt being 73s, the rest being self explanatory. And it turns out.. seconds is also 98s! Seems like fiddling of numbers until eventually getting the right answer.. but nah:tongue: And how in the world did he derive that formula.. Time of transverse wave is equal to the velocity of the longitudinal wave times the change in time divided by the difference in velocity.