1. On a hiking trip, you are walking through a canyon with vertical walls and ar
ID: 1292626 • Letter: 1
Question
1. On a hiking trip, you are walking through a canyon with vertical walls and are closer to one wall than the other. Having taken Physics, you decide to determine the width of the canyon by using your knowledge of kinematics and the speed of sound. You shout "Hey" as loud as you can, and after a short time you hear three echoes. The second echo arrives 1.5 s after the first, and the third echo arrives 0.9 s after the second. Assuming that the speed of sound is 343 m/s and that there are no reflections of sound from the ground, find the width of the canyon.
Units in m
2. A storm warning siren emits sound uniformly in all directions. Along a line that is drawn radially outward from the sound source (the siren) determine the positions of two points, 0.93 m apart, such that the intensity level at one point is 2.92 dB greater than the intensity level at the other.
a) point closer to siren units in m
b) point farther from siren units in m
Explanation / Answer
What that depends on is :
1) the first echo is from the near wall
2) the 2nd echo is from the far wall
3) the 3rd echo is from the near wall again as the echo fro (2) is re-echoed.
It takes 2 seconds for the sound to travel twice the width of the canyon (draw a diagram to help see this)
speed of sound is 343.2 metres per second (1,126 ft/s).
Thus the canyon is 343 m or 1,126 feet wide
Thus it takes sound 1 second to cross the canyon
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