Orca whales make sounds so loud that hydrophones (a sound wave detecting microphone that is used underwater) can pick them up from a great distance in seawater (the speed of sound in seawater is 1470 m/s) . Assume that an orca travelling at 55 km/h is approaching an observer using a hydrophone . How long after the sound is heard will the whale take to reach the observer from the initial distance of 8.0 km?