how is rain water collected from rooftop?
The rainwater on the roofs of the buildings is collected through canals that drain the water into ground reservoirs. This stored water is later utilized for various purposes.
The rain water from a roof of dimensions 22 m×20 m drains into a cylindrical vessel having diameter of base 2 m and height 3.5 m If the rain water collected from the roof just fills the cylindrical vessel, then find the rain fall in cm.