The frictional resistance to the rotation of a flywheel consists of a retardation due to air friction which varies as the square of the angular velocity and a constant frictional retardation in the bearing. As a result the angular acceleration of the flywheel while it is allowed to coast is given by a = −K − kw², where K and k are constants. Determine an expression for the time required for the flywheel to come to rest from an initial angular velocity w₀.