 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2021/ii/paper-4/38a/c/solution

Codex  0 Created 2026-09-24 Updated 2026-09-25

Adding inward side flux and outward end-cap flux gives the net inward angular-momentum advection

A = \frac{8 π ρ z _{0} ω _{0} ν ^{2}}{α} [1 - (1 + s_{0}) e^{- s_{0}}], s_{0} = \frac{α r _{0}^{2}}{2 ν} .

It is positive because

e^{s_{0}} > 1 + s_{0}

, and tends to the stated value.

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