An experiment is being set up that requires echoes to arrive at least 0.2 s after the emission of sound. What minimum distance should a reflecting surface be placed at? Assume the speed of sound to be 343 m s⁻¹.
34.3 m
Explanation
To hear an echo, sound must travel from the source to the reflecting surface and back. Therefore, the total distance travelled is twice the distance between the source and the reflecting surface. The formula used is distance from wall = (speed × time) / 2. Given the speed of sound is 343 m s⁻¹ and the minimum time for the echo to arrive is 0.2 s, we substitute these values into the formula to find the minimum distance.
Solution Steps
Step 1: Identify the given values: Speed of sound (v) = 343 m s⁻¹, Time (t) = 0.2 s.
Step 2: Calculate the total distance travelled by sound: Total distance = v × t = 343 m s⁻¹ × 0.2 s = 68.6 m.
Step 3: Since sound travels to the wall and back, the minimum distance of the reflecting surface is half of the total distance: distance from wall = 68.6 m / 2 = 34.3 m.