- #1
Saitama
- 4,243
- 93
Homework Statement
A soap bubble is blown with a relatively short drinking straw of diameter d, and then the bubble is left to deflate through the same straw. In one case when the diameter of the bubble was D the time during which the bubble deflated was 8 seconds. Estimate the time during which a bubble deflates
a) if its diameter is also D, and it is deflated through a wider straw of diameter 2d;
b) through a straw of diameter d, if its greatest diameter was 2D?
Homework Equations
The Attempt at a Solution
The air inside the bubble moves out because of the pressure difference between the two ends of straw. The pressure difference is ##4T/r##, where ##T## is the surface tension of soap liquid and ##r## is the radius of bubble at any time. I feel I have to find the time (##dt##) in which the radius of bubble decreases by ##dr## and then integrate it but how do I find an expression for ##dt##?
Any help is appreciated. Thanks!