A rectangular solid with a weight of $225$ N$,$ cross$-$sectional area of $205$ x $205$ mm$,$ is inclined at an angle of $20\backslash$deg to the horizontal. If there is an oil film on the cross$-$section of the solid with a thickness of $0\mathrm{.}025$ mm$,$ and given that the viscosity coefficient of the oil is $2\mathrm{.}155$ mPa$\backslash$times s and the velocity profile of the oil is linear, find the velocity of the solid as it slides down the incline.