Question

Difficulty: EasySound Waves, Echoes, Pitch, Loudness, and Quality

A hiker standing at a distance from a tall vertical cliff shouts and hears an echo 0.60 s0.60\text{ s} later. If the speed of sound in air is 330 m/s330\text{ m/s}, what is the distance between the hiker and the cliff?

  1. A
    198 m198\text{ m}
  2. 99 m99\text{ m}Answer
  3. C
    550 m550\text{ m}
  4. D
    49.5 m49.5\text{ m}

Answer

The distance between the hiker and the cliff is 99 m99\text{ m}.
An echo is a reflected sound wave. The sound travels from the hiker to the cliff and back, covering a total distance of 2d2d in time tt. Therefore, 2d=v×t2d = v \times t, which gives d=330 m/s×0.60 s2=99 md = \frac{330\text{ m/s} \times 0.60\text{ s}}{2} = 99\text{ m}.

Step-by-Step Solution

1
Identify given parameters and echo relation
Speed of sound v=330 m/sv = 330\text{ m/s}, time elapsed t=0.60 st = 0.60\text{ s}. An echo involves sound traveling to the wall and back (2d2d).
The total distance traveled by the sound wave during time tt is twice the distance to the reflecting surface.
2
Calculate the one-way distance
d=v×t2=330×0.602=99 md = \frac{v \times t}{2} = \frac{330 \times 0.60}{2} = 99\text{ m}.
Dividing the total distance by 2 yields the actual distance from the hiker to the cliff.

Key Concept

Echo distance calculation
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