Calculate the velocity a spherical rain drop would achieve falling from 5.00 km (a) in

Calculate the velocity a spherical rain drop would achieve falling from 5.00 km (a) in the absence of air drag (b) with air drag. Take the size across of the drop to be 4 mm, the density to be 1.00 × 10³ kg/m³, and the surface area to be πr².