Delta Sign Confusion: Solving Depth of Grand Canyon

[ashley_bryant]

Homework Statement

Hans stands at the of the Grand Canyon and yodels down to the bottom. He hears his yodel echo back from the canyon floor 5.20s later. Assume that the speed of sound in air is 340.0m/s. How deep is the canyon at this location?

I made a chart.
Velocity Original = 340
Velocity Final= Unknown
Distance= x
Gravity = 9.81
Time = 5.20

The equation I'm using is
vf=vo+g(DELTA)t

I pretty much do the equation, I just need to know what I need to do for delta. (divide, mulitply, etc. I'm in Physics PRE-AP, Algebra, 9th grade. Advanced classes, blah.)

Homework Equations

Not sure what you mean?

The Attempt at a Solution

I plugged in the numbers:
vf= 340 + 9.81 (DELTA) 5.20

For delta, I used division. (VF-VO/G = T?)
I plugged in the numbers:
0-340/9.81
I got -34.65
This is probably wrong... >_<

 

[Kurdt]

The equation you need is simply s=\frac{d}{t} . Sound is a pressure wave and doesn&amp;#039;t behave like a kinematic particle. Its speed is essentially constant.