311_guide8 - ME/NE 311 Introduction to Thermal and Fluid...

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Unformatted text preview: ME/NE 311 Introduction to Thermal and Fluid Sciences Reading Guide #8 Chapter 4 Sections 2.3, 2.5, 3 and 4 (NOTE: Skip section 4.2.4: Forces on Submerged Curved Surfaces) Section 4.2.3: Fluid Statics: Forces on Submerged Plane Surfaces 1. Why was it important for the Philadelphia zoo to accurately compute the hydrostatic forces on the glass window in the bear exhibit? _____________________________________________________ 2. The angle is measured from to what surface (__________________________) to what surface (______________________________________________________). 3. What branch of mathematics was used to translate the depth, z, into a relation in terms of used in Equation 47. ______________________________ 4. In Equation 47 and Figure 4.8, are axes `z' and `y' orthogonal? Yes or no 5. The value of g sin( )yc represents the hydrostatic pressure evaluated at the centroid of a flat surface. True or false 6. The density in g sin( )yc is that of (a) the flat surface, or (b) of the fluid in which the flat surface is submerged. ____________ 7. The value of yc is measured from (a) the top of the flat surface, or (b) from the free surface of the fluid in which the flat surface is submerged. ________ 8. Assuming air at atmospheric pressure is exposed to the back side of a flat plate, the hydrostatic pressure evaluated at the centroid of a flat surface times the area of one side of the submerged flat surface represents the resultant force acting on the entire (both sides of the) plate. True or false (Figure 4.10 may help you answer this question). 9. The resultant force acts not at the centroid of the plate but at a depth (a) above or (b) below the centroid of the plate. 10. The variable Ixx represents the area moment of inertia about the xaxis. True or false 11. The area moment of inertia about the axis of rotate of the ellipse, as shown in Table 4.1(g), is I xx = ab3 4 . If the ellipse is rotated 90 degrees, the area moment of inertia about the axis of ME 311 Reading Guide #8 1/2 rotation becomes I xx = ba3 4 . True of false. Assume that the gravity acts toward the bottom of the page for both cases. 12. Which of the two equations, Equation 415 or Equation 417, is applicable to a flat surface on which the atmosphere acts on both the back surface and the top of the free surface of the fluid in which the flat plate is submerged. _________________________________ Section 4.2.5: Fluid Statics: Buoyancy 1. A body that is either submerged or is floating in a fluid will experience a vertical buoyant force equal to the ________________ of the fluid it displaces. 2. The center of the buoyant force of a submerged body must coincide with the center of the gravity of the submerged body. True or false 3. The center of the buoyant force of a floating body must coincide with the center of the gravity of the floating body. True or false (Challenging question. Consider a barge with an unequalled distribution of weight.) 4. If a body is floating between two fluids, say fluid A and fluid B, how is the buoyant force calculated? _______________________________________________________ Section 4.4: Conservation of Mass for an Open System 1. Mass may cross the boundary of an open system. True or false 2. If more mass enters a control volume than leaves the same control volume, such as occurs in the filling of a balloon in which the mass leaving is zero, then there is a positive rate of change of mass inside the balloon. True or false 3. The (a) transient or (b) steadystate form of the conservation of mass would be used to solve the type of problem noted in question #2 above. __________ 4. Mathematically define mass flow rate. m = ________________________________________ 5. In the equation written above for mass flow rate, V represents velocity, which is assumed to be ____________________________ over the entire crosssectional flow area, denoted by _______. 6. If the rate of change of mass inside the control volume is zero (i.e., the amount of mass inside the control volume does not change with time), as is the case that occurs for flow through a nozzle, the mass flow is considered to be __________________________________. ME 311 Reading Guide #8 2/2 ...
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This note was uploaded on 05/16/2011 for the course ME 311 taught by Professor Alexia during the Spring '11 term at University of Oregon.

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