# ENGR_2097_2013_Midterm-1.docx - ENGR 2097 u25cf Fluid...

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ENGR 2097 Fluid Mechanics I 2013 Winter Midterm Test - Water Density 1000 kg/m3 - Gravitational Acceleration 9.8 m/s 2 - The Second Moment of Area (Moment of Inertia) for a Rectangle: I xx = a 3 b 12 I yy = ab 3 12 1. A liquid layer is flowing down over an inclined surface under gravity. There is no velocity in the y-direction and the velocity in the x-direction u is given by u = U [ 2 y h ( y h ) 2 ] , where U (the maximum velocity at the liquid surface) and (the layer thickness) are constants. The liquid viscosity is . Please find an expression of the shear stress from the liquid on the solid surface, and indicate the direction of this shear stress with arrows. ( 5 marks ) h μ 2. A 10-cm-long wood block with a constant cross-sectional area is floating on the surface of Liquid A with 2.5 cm of its length in air. A U-shape glass tube is connected to the container of Liquid A, with a column of Liquid B in right. The density of the wood block is 800 kg/m 3 . Use the information in the figure and find the densities of Liquid A ( ρ a ) and Liquid B ( ρ b