1. The problem statement, all variables and given/known data A soccer player kicks a rock horizontally off a 40.0m-high cliff into a pool of water. If the player hear the sound of the splash 3.00s later, what was the initial speed given to the rock? Assume the speed of sound in air to be 343 m/s. I wrote down givens in the y-direction: ΔY = -40.0m t = 3.00s a = -9.80m/s^2 Vo = 0 θ = 0° And in the x-direction: a = 0 t = 3.00s 2. Relevant equations ΔY=v0t+(1/2)at2 v=v0+at 3. The attempt at a solution I am assuming that the intial y-velocity is equal to 0, since the rock was kicked horizontally...is that correct? That means I am looking for the initial velocity in the x-direction. However, I am not given displacement in the x-direction. So how do I set up the problem? Also, is the speed of sound important? Thank you for your help!