For a water clocks, bowl-shaped vessels that drained from a small hole of area A in the bottom

For a water clocks, bowl-shaped vessels that drained from a small hole of area A in the bottom. The radius R(z) of the circular bowl varies with height, where z is measured from the bottom of the bowl (z = 0).

(b)  For a small bowl (radius = 25 cm) originally filled to a depth of 20 cm, why is it reasonable to use a version of Bernoulli rather than an estimate starting with Stokes equations?

(c)  What is the approximate relation between the radius of the hole at the bottom and the Reynolds number where you should start to expect some viscous modification to the flow?