t = 1 s.
V = 340 m / s.
The sound from a clap in the palm reaches the obstacle, is reflected from it and returns back. The sound travels the distance S = 2 * S1, where S1 is the distance to the obstacle.
The time of sound movement t is expressed by the formula: t = S / V = 2 * S1 / V.
S1 = V * t / 2.
S1 = 340 m / s * 1 s / 2 = 170 m.
Answer: the obstacle is at a distance of S1 = 170 m.
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