How Do You Calculate the Initial Drop Height in a Free Fall Problem?

[runningirl]

Homework Statement

A stone is dropped off the science building and accelerates, from rest, toward the ground at 9.8 m/s/s. A curious physics student looks out the third floor window as the stone falls past. She happens to have a stopwatch and she finds that it takes 0.30 sec for the stone to fall past the 2.2 m tall window. She then sketches the velocity vs. time plot shown below, but realizing she is late for lunch, she doesn't use the plot to analyze the motion of the stone.

a) What was the average velocity of the stone as it fell past the window?

b) What was the velocity of the stone at the top of the window?

c) From what height above the top of the window did the stone start its fall?

Homework Equations

delta(x)=initial velocity*time + .5(at^2)

The Attempt at a Solution

a) I got 2.2/.3 m/s

b) I used the equation above and got 8.99999 m/s

c) I was clueless with part C

 

[kuruman]

If a stone starts from rest, over what distance must it fall so that reaches a final speed of 2.2/3 m/s? That's the distance you re looking for.