posted by Stonehenge .
A stone at rest is dropped from a 20m tall building. After falling for 10m, it reaches the top of a 2m tall window. How long will it take to fall past this window? Thank you!
Compute the times required to fall Y = 10 and Y = 12 m. Then subtract the 10 m time from the 12 m time. The will be the time spent crossing the window.
Y = (g/2) t^2
t(12 m) = sqrt (2Y/g) = 1.565 s
t(10 m) = sqrt (2*10/g) = 1.429 s
The difference is 0.136 s