Air (density `rho`) is the being down on soap film (surface tension `T`) by pipe of radius `R` with its opening right next to the film. The film is deformed and a bubble detached from the film when the shape of the deformed surface is a hemisphere. Given that the dynamic pressure on the film due to the air blown at speed `v` is `1/2 rho v^(2)` the speed at which the bubble is formed is