Noah stands 170 meters away from a steep canyon wall. He shouts and hears the echo of his voice one second later. What is the speed of the wave?

answer: 340 m/s

explanation: in this instance, the sound wave travels 340 meters in 1 second, so the speed of the wave is 340 m/s. remember, when there is a reflection, the wave doubles its distance. in other words, the distance traveled by the sound wave in 1 second is equivalent to the 170 meters down to the canyon wall plus the 170 meters back from the canyon wall.