A steel ball is dropped from the roof of a building.An observer standing in front of a window 1.2 m high notes that the ball takes `1/8` s to fall from the top to the bottom of the window.The ball continues to fall, makes a completely elastic collision with a horizontal sidewalk and reappears at the bottom of the window 2 s after passing it on the way down. How tall is the building ?

Answer

20.43 m