3. ( \( \mathbf{3 0} \) minutes) A film of liquid with a constant thickness of \( d \) and width of \( w \) flows down on an inclined plate as shown in the figure below. The liquid has density of \( \rho \) and viscosity of \( \mu \).
a. Obtain an expression for the velocity distribution \( u(y) \) by listing all the assumptions and making all necessary simplifications on the governing equations.
b. Obtain an expression for the volume rate of the flow.
Hint: This is an open channel flow driven by only gravity therefore you may neglect the pressure gradient in the streamwise direction.
Note: List all the assumptions and make all necessary simplifications on the governing equations. Write and organize your answer sheet neatly.