In the laminar flow of an oil of viscosity \(1 \mathrm{~Pa} \cdot \mathrm{s}\), the velocity at the center of a \(0.3 \mathrm{~m}\) pipe is \(4.5 \mathrm{~m} / \mathrm{s}\) and the velocity distribution is parabolic. Calculate the shear stress at the pipe wall and within the fluid \(75 \mathrm{~mm}\) from the pipe wall.