Answer 1

The simple experiment that a person can do to calculate the speed of sound in air is that a person stands at a known distance (d meter) from the cliff and fires a pistol and simultaneously start the stopwatch. He stops the stop-watch as soon as he hears an echo. The distance traveled by the sound during the time (t) seconds is 2d.
So, speed of sound = distance travelled / time taken = 2d/t