A group of hikers hear an echo 2.6 s after they shout. The temperature is 20 ◦C. How far away is the mountain that reflected the sound wave? At this altitude, the speed of sound in air at 273 K is 328 m/s. Answer in units of m.

22. the top of a cliff is located a distance h above the ground. at a distance h/2 there is a branch that juts out from the side of the cliff, and on this branch a bird's nest is located. two children throw stones at the nest with the same initial speed, one stone straight downward from the top of the cliff and the other stone straight upward from the ground. in the absence of air resistance, which stone hits the nest in the least amount of time?