posted by Anonymous .
A roof tile falls from rest from the top of a building. An observer inside the building notices that it takes 0.12 s for the tile to pass her window, which has a height of 2.2 m. How far above the top of this window is the roof?
if it takes t seconds to reach the top of the window, it takes t+.12 seconds to reach the bottom. In that interval, it falls 2.2m
4.9(t+.12)^2 - 4.9t^2 = 2.2
t = 1.81
In the 1.81 seconds, it fell
4.9*1.81^2 = 16.05
so, the roof is 16.05m above the top of the window.