What is the difference between the pressure inside a soap bubble and atmospheric pressure for a 3-in-diameter bubble? Assume the surface tension of the soap film to be 70% of that of water at 70 degrees F. Note that the liquid film of a bubble is in contact with air on the inside as well as on the outside. Thus surface tension acts on 2 surfaces on a FBD of half the bubble. Assume the liquid film is thin enough that its weight can be neglected.