4. An open vertical cylindrical vessel, 2m in diameter and 4m high is filled with water to the top. If rotated on its own vertical axis in order to discharge a quantity of water to uncover a circular area at the bottom of the vessel 1 m in diameter. (a) Determine the angular speed in rpm, and (b) how much water is left in the cylinder after rotation? r = Im 05 05 4 m