Posted by Marcus on Tuesday, February 2, 2010 at 2:00am.
A rock is dropped from a sea cliff and the sound of it striking the ocean is heard 6.4 s later. If the speed of sound is 340 m/s, how high is the cliff?

College Physics  drwls, Tuesday, February 2, 2010 at 3:35am
The time of 6.4 s is the sum of the time required for the rock to hit the sea, sqrt (2H/g), and the time for the sound to get back, (H/V).
H = cliff height
V = speed of sound
g = acceleration of gravity
Solve this equation for H:
6.4 = H/340 + sqrt(H/4.9)
That can be turned into a quadratic equation. Only one root will be positive. 
College Physics  jim, Tuesday, September 7, 2010 at 8:40pm
172.35

College Physics  Anonymous, Sunday, October 26, 2014 at 9:03pm
356.8