Two parallel surfaces move relative to each other are separated by a gap of 0.375 in. The gap is filled by a fluid of with .00431 lb-sec/in2 viscosity. The relative motion is resisted by a shear stress of 0.25 lb/in2 due to the viscosity of the fluid. What is the velocity of the parallel surfaces above assuming the velocity gradient in the space between the surfaces is constant?

۱۵ Q3/ A dash pot is 0.2 m in diameter and 0.25 m long and it slides down in a vertical cylinder of diameter 0.21 m. The lubricating oil filled in the annular space has a viscosity of 0.5 poise and has a linear velocity profile. When the load on the piston is 25 N, find the speed with which the piston slides down. سرعة الله Dash pot Oil Cylinder- 0.2 m 25 N 0.21 m T 0.25 m

Problem 2 The apparatus sketched in the figure below serves as a viscometer i.e. it can be used to measure the viscosity of a liquid. In the drawing, D is a large reservoir containing a viscous liquid A and E is a cylindrical tube of radius R, open at both ends, surrounding and coaxial with B, which is a cylindrical "bob" of radius êR that is dragged up through the fluid by a frictionless pulley system (C) utilizing a weight W. Determine a design equation that relates the viscosity of the liquid to the geometry of the system and the weight W. Hint: you can assume that the length of the cylindrical tube is sufficiently long for the flow to reach steady state. W E D B