$2.$ Oil $($constant viscosity $\backslash (\backslash$mu $\backslash )$ and density $\backslash (\backslash$rho $\backslash ))$ is confined in a cylinder with diameter $\backslash ($ D $\backslash )$ by a piston with clearance of $\backslash ($ h $\backslash ).$ The length of the piston is given by $\backslash ($ L $\backslash ),$ and a weight $\backslash ($ W $\backslash )$ is applied to the piston. You may assume that $\backslash ($ h $\backslash$ll D $\backslash ).$

Estimate the leakage rate of oil $\backslash ($ Q $\backslash )$ past the piston, in terms of the known parameters.