Chelsea was walking by Grand Canyon at a certain point. If she yelled and heard the echo back 14.46648 A.)…

Chelsea was walking by Grand Canyon at a certain point. If she yelled and heard the echo back 14.46648 A.) how deep was the canyon (speed of sound is 340 m/s)? B. If she kicked off a rock from the same cliff how long would it take to hit the ground? C. How fast would the rock be going?