A girl standing some distance from the cliff claps her hands and hears the echo 0.8s later. calculate her distance from the cliff. [speed of sound in air = ...

A girl standing some distance from the cliff claps her hands and hears the echo 0.8s later. calculate her distance from the cliff. [speed of sound in air = 320 ms^-1]

Answer Details

When sound waves travel, they can bounce off surfaces and return to the listener's ear, creating an echo. The distance between the listener and the reflecting surface can be calculated from the time taken for the sound to travel to the surface and back, and the speed of sound. In this problem, the time taken for the sound to travel to the cliff and back (i.e., the time for the echo to be heard) is given as 0.8s. The speed of sound in air is given as 320 ms^-1. Let's call the distance between the girl and the cliff "d". When she claps her hands, a sound wave travels the distance "d" to the cliff and then back again to her ear, covering a total distance of 2d. The time taken for this round trip is equal to the time for the echo to be heard, which is 0.8s. So, we can use the formula: distance = speed x time to calculate the distance "d" between the girl and the cliff. Rearranging the formula, we get: distance = (speed x time) / 2 Substituting the values given in the problem, we get: distance = (320 ms^-1 x 0.8s) / 2 distance = 128m Therefore, the girl is 128 meters away from the cliff. So, the correct option is (b) 128m.