According to the Kutta-Joukowski theorem, the aerodynamic lift per unit span $L'$ generated by a two-dimensional cylinder or airfoil immersed in a steady uniform stream of density $\rho_\infty$ and freestream velocity $V_\infty$ with bound circulation $\Gamma$ is given by:

(A) L' = \rho_\infty V_\infty \Gamma

(B) L' = \frac{1}{2} \rho_\infty V_\infty^2 \Gamma

(C) L' = \frac{\rho_\infty \Gamma}{V_\infty}

(D) L' = 2\pi \rho_\infty V_\infty \Gamma

Answer Key:

A

### 5-Stage Derivation & Analytical Solution: 1. **Stage 1: Potential Flow Theory:** By integrating surface pressure around a circular cylinder with circulation in uniform flow, $L' = -\oint p \sin\theta R d\theta = \rho_\infty V_\infty \Gamma$. 2. **Stage 2: Direction:** Lift acts perpendicular to freestream velocity. 3. **Stage 3: Selection:** Option A is the canonical formulation.

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