Simple Problem with Gravity and Time

1. The problem statement, all variables and given/known data

"A rock is dropped off a cliff into the water below. The sound of the splash is heard 3.0 s later. If the speed of sound is 332 m/s, calculate the height of the cliff above the water. (Note: the total time it takes for the rock to fall and the sound to travel upwards is 3.0 s)"

Therefore,
v1 = 0
g = 9.8 m/s2
Δt = 3.0 s
vsound = 332 m/s

2. Relevant equations
FOR SOUND
Δd = vsound * Δt2, where Δt2 is the time it takes from the sound to reach the top of the cliff from the bottom.
FOR ROCK
Δd = v1 * Δt + 0.5 * g * (Δt)2
*the following equations may be useful but i doubt it*
v2 = v1 + g * Δt
(v2)2 = (v1)2 + 2 * g * Δd

*assume no air resistance

3. The attempt at a solution
Δd = ?
No clue.

I figured that the answer should be 41 m, I believe, by trial and error but I would like to know how this can be solved in a normal way.

http://ift.tt/1jN8YNM

Leave a comment

Your email address will not be published.


*


Show Buttons
Hide Buttons