Choose the correct answer:
1. A student stands at a distance from a large cliff and produces a sound. The echo is heard \(0.6\ s\) later. If the speed of sound in air is \(340\ m/s\), what is the distance between the student and the cliff?
2. A SONAR device sends a sound pulse towards the sea floor. The pulse takes \(3\ s\) to return. Another device at the same location sends a pulse later, and the pulse takes \(2\ s\) to return. Assume that the speed of sound in the water remains unchanged.
Which statement correctly explains the difference?