Two immiscible fluids of equal density are flowing down a surface inclined at a \(60^{\circ}\) angle. The two fluid layers are of equal thickness \(h=10 \mathrm{~mm}\); the kinematic viscosity of the upper fluid is \(1 / 5\) th that of the lower fluid, which is \(u_{\text {lower }}=0.01 \mathrm{~m}^{2} / \mathrm{s}\). Find the velocity at the interface and the velocity at the free surface. Plot the velocity distribution.