Hey there! I have a question, if you could help me with it. I have a soap film with a closed elastic thread inside. There is a sliding wire at one side of film. What will happen to the radius of the elastic thread when the wire is moved outwards?
Anonymous
I thought, the film will of course try to reduce its area and hence the radius will increase, but it is not so :(
Anonymous
My teacher confused me and got confused himself on this question. Help :/
@DivyankaS.Chaudhari The surface tension of a soap film is constant, so it is not changed when you slide the wire inwards of outwards.
A soap film is not like a rubber sheet. With a rubber sheet the tension increases when you stretch it, but with a soap film the tension stays constant.
Anonymous
So, what happens to the elastic thread circle in there?
