Es 65 Class Review Guide Questions

ES 65 Class Review Guide Questions 1. [Fluid Flow in Pipes] A manufacturer makes two types of drinking straws: one with a square cross-sectional shape, and the other type the typical round shape. The amount of material in each straw is to be the same. That is, the length of the perimeter of the cross section of each shape is the same. For a given pressure drop, what is the ratio of the flow rates through the straws? Assume the drink is viscous enough to ensure laminar flow and neglect gravity. 2. [Dimensional Analysis] A simple pendulum consists of a small, heavy ball of mass m on the end of a long string of length L. The period of the pendulum should depend on these factors, as well as on gravity, which is the driving force for making it move. What information can you get about the relationship between these variables from a consideration of their dimensions? Suppose you measured the period, T1, of a pendulum with mass m1 and length L1. How could you use this to determine the period of a different pendulum with a different mass and length? What would be the ratio of the pendulum period on the moon to that on the earth? How could you use the pendulum to determine the variation of g on the earth’s surface? 3. [Properties of Fluid] A 10 cm diameter ball having a specific gravity of 1.2 was dropped in a well 3-m deep having a diameter of 1m. The specific gravity of the ball is 1.2. To recover the ball, a fluid mechanics student suggested to dump salt into the well to make the ball float. Assume no volume change when salt is added into the water, how much salt is needed just to float the ball. 4. [Principles of Hydrostatics] A block of wood requires a force of 40N to keep it immersed in water and a force of 100 N to keep it immersed in glycerin (s.g = 1.3). Find the weight and specific gravity of the wood. 5. [Fundamentals of fluid flow] Demonstrate how did Osborne Reynolds conducted his experiment in determining the flow regime whether it is laminar or turbulent?

6. [Fluid Flow Measurement] Calculate he discharge through the submerged orifice in the figure.