What do the arrows at point three indicate

What if? if the temperature near the cliff suddenly falls to 0°c, reducing the speed of sound to 331 m/s, what would the initial speed of the rock have to be (in m/s) for the soccer player to hear the sound of the splash 2.90 s after kicking the rock?

In a system, when potential energy decreases, then entropy also decreases. true false

Ineed the answer to question 1 , i’m desperate