(a) Draw a free-body diagram analogous to Figure 18.32 for a gas-liquid-solid boundary at which the contact angle is \(90^{\circ}\). Make your solid surface horizontal.

(b) How do the magnitudes and directions of the adhesive and cohesive forces exerted on your particle compare?

(c) How does the magnitude of the cohesive force between two liquid particles compare with the magnitude of the adhesive force between a liquid particle and an atom in the solid?

Data from Figure 18.32

Transcribed Image Text:

(a) Liquid wets surface (b) Liquid does not wet surface points along bisector of liquid wedge Fcohes cohesive F cohesive particle at junction Fadh adhesive points perpendicular to solid surface Vector sum must point perpendicular to liquid surface (or particle would move along surface). Fadhesive