A soap bubble of radius cm floats in still air

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 soap bubble of radius R=1.5R = 1.5 cm floats in still air. The film has two surfaces, each of surface tension γ=0.025\gamma = 0.025 N m−1^{-1}, and the film is thin enough that the two radii may both be taken as RR. The weight of the film is ignored. ((a)) By how much does the pressure of the air inside the bubble exceed the pressure of the air outside? ((b)) What would the excess pressure be inside a droplet of clean water (γ=0.072\gamma = 0.072 N m−1^{-1}, one surface) of the same radius?

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