4. Calculate the pressure difference between the inside and outside of a water droplet with a diameter of 1/16 in at 70 °F. Hint: use the surface tension value in Appendix B of the book.

Pipeline A has oil of relative density 0.85 and pressure gauge reading at B is 330 kPa.

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

4Q. Compute the capillary depression of mercury at 68 °F (0 = 140°) to be expected in a 0.05 in diameter tube?