5. A cowboy stands on horizontal ground between two parallel
vertical cliffs. He is not midway between the cliffs. He
fires a shot and hears its echoes. The second echo arrives
1.92 s after the first and 1.47 s before the third. Consider
only the sound traveling parallel to the ground and reflecting
from the cliffs. Take the speed of sound as 340 m/s.
(a) What is the distance between the cliffs? (b) What If? If
he can hear a fourth echo, how long after the third echo
does it arrive?