= Solution
This is the first printed “(vi)”, concerning adhesion. The reversible work per unit area to separate the solid–liquid interface into solid–vapor and liquid–vapor interfaces is
$$
W=\gamma_{SV}+\gamma_{LV}-\gamma_{SL}.
$$
Substitute $\gamma_{SV}-\gamma_{SL}=\gamma_{LV}\cos\theta_C$ from <Young's equation>:
$$
\boxed{W=\gamma_{LV}(1+\cos\theta_C).}
$$
This is the <Young-Dupré equation>. It has units $\mathrm{J\,m^{-2}}$, equivalent to $\mathrm{N\,m^{-1}}$. The liquid–vapor tension is the multiplier; the abbreviated printed subscript does not denote a new interface. Within this equilibrium model, smaller <water> <contact angle> means larger reversible work of adhesion for fixed liquid–vapor tension.
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