sound waves
چهارشنبه 21 شهریورماه سال 1386 14:40
under proper conditions,sound waves will be reflected from a hillside or other such obstruction. sound travels at the rate of about one-fifth of a mile per second. if the hill is eleven hundred feet away,it takes two seconds for the sound to travel to the hill and back.thus,by timing the interval between a sound and...