Here is one question which has amused me a lot and I'm still unable to figure out the correct way to approach this.
What is the terminal velocity of an air bubble (spherical in shape) which rises up in a water column of density \(\rho_w\) and height \(h\) with an initial radius of \(r\). Consider the coefficient of viscosity as \(\eta\) and acceleration due to gravity as \(g\).
The issue is that we can't just apply Stokes law directly cuz, the radius of the air bubble increases up the water column.
So, if you have got the solution or atleast some idea of how to solve this please comment below.