A soap film is suspended on a wire frame, as shown in Fig.2.10. The movable wire is

Question:

A soap film is suspended on a wire frame, as shown in Fig.2.10. The movable wire is displaced by an applied force F. If the surface tension remains constant
(a) Obtain an expression for the work done in stretching the film in terms of the surface tension τ, length ℓ, and displacement ∆x.
(b) Evaluate the work done, in J, if ℓ=5 cm, ∆x = 0.5 cm, and τ= 25 ×10-5 N/cm.