No, you are at a constant rate which means that you are always at 40mph
Given:
The speed of sound is 340 m/s
Time for the echo is 5.2 s.
Let h = the depth of the canyon.
Because the sound of your voice travels to the bottom of the canyon and back to your ear, the total distance traveled is 2h.
By definition,
distance = velocity * time.
Therefore
2h = (340 m/s)*(5.2 s) = 1768 m
h = 884 m
Answer: The depth is 884 m.
