PHYSICS · Multi-part · Fermi University Physics · Fluids & Continuum Physics · Fluid statics and the continuum picture · Fluid statics and the continuum picture
Fluids and Continuum Physics, Ch Surface tension, capillarity and wetting
Problem
A rectangular wire frame carries a soap film. One side of the frame is a straight slider of length ℓ=8.0 cm which can move without friction along the two rails, so the film spans the frame and has two faces. The surface tension of the soapy water is γ=0.025 N m−1. The weight of the film and of the slider are ignored, and the film stays flat.
((a)) What force must be applied to the slider, along the rails, to hold it at rest?
((b)) How much work must be done on the slider to pull it a further d=1.5 cm, so lengthening the film?