If a tsunami started t the west of Mexico. How long will it take the tsunami, travelling at 200 m/s, to travel 900Km across the Pacific Ocean to reach Japan ?
In other words: d = rt
Divide both sides by r to get: d/r = t
Substitute: 900000/200 = t (note that I had to change km to meters)
Finally: 4500 = t
So it took 4500 seconds to get across
Or you could say 75 minutes
Or you could say 1 and a quarter hours.