Thermodynamics: An Engineering Approach
8th Edition
ISBN: 9780073398174
Author: Yunus A. Cengel Dr., Michael A. Boles
Publisher: McGraw-Hill Education
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Chapter 3.8, Problem 107P
A thermos bottle is half-filled with water and is left open to the atmospheric air at 60°F and 35 percent relative humidity. If heat transfer to the water through the thermos walls and the free surface is negligible, determine the temperature of water when phase equilibrium is established.
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Problem 2 (55 pts). We now consider the FEM solution of Problem 1.(a) [5pts] Briefly describe the 4 steps necessary to obtain the approximate solution of thatBVP using the Galerkin FEM. Use the minimum amount of math necessary to supportyour explanations.(b) [20pts] Derive the weak form of the BVP.(c) [10pts] Assuming a mesh of two equal elements and linear shape functions, sketch byhand how you expect the FEM solution to look like. Also sketch the analytical solutionfor comparison. In your sketch, identify the nodal degrees of freedom that the FEMsolution seeks to find.(d) [10pts] By analogy with the elastic rod problem and heat conduction problem considered in class, write down the stiffness matrix and force vector for each of the twoelements considered in (c).(e) [10pts] Assemble the global system of equations, and verbally explain how to solve it.
An aluminum rod of length L = 1m has mass density ρ = 2700 kgm3 andYoung’s modulus E = 70GPa. The rod is fixed at both ends. The exactnatural eigenfrequencies of the rod are ωexactn =πnLqEρfor n=1,2,3,. . . .1. What is the minimum number of linear elements necessary todetermine the fundamental frequency ω1 of the system? Discretizethe rod in that many elements of equal length, assemble the globalsystem of equations KU = ω2MU, and find the fundamentalfrequency ω1. Compute the relative error e1 = (ω1 − ωexact1)/ωexact1.Sketch the fundamental mode of vibration.
Chapter 3 Solutions
Thermodynamics: An Engineering Approach
Ch. 3.8 - Is iced water a pure substance? Why?Ch. 3.8 - What is the difference between saturated vapor and...Ch. 3.8 - 3–3C Is there any difference between the...Ch. 3.8 - 3–4C Why are the temperature and pressure...Ch. 3.8 - Is it true that water boils at higher temperature...Ch. 3.8 - What is the difference between the critical point...Ch. 3.8 -
3–7C Is it possible to have water vapor at ?
Ch. 3.8 - A househusband is cooking beef stew for his family...Ch. 3.8 - In what kind of pot will a given volume of water...Ch. 3.8 - It is well known that warm air in a cooler...
Ch. 3.8 - Does the amount of heat absorbed as 1 kg of...Ch. 3.8 - Does the reference point selected for the...Ch. 3.8 - What is the physical significance of hfg? Can it...Ch. 3.8 - Does hfg change with pressure? How?Ch. 3.8 - Is it true that it takes more energy to vaporize 1...Ch. 3.8 - What is quality? Does it have any meaning in the...Ch. 3.8 - Which process requires more energy: completely...Ch. 3.8 - In the absence of compressed liquid tables, how is...Ch. 3.8 - Prob. 19PCh. 3.8 - Complete this table for H2O:Ch. 3.8 - Prob. 21PCh. 3.8 - Complete this table for H2O:Ch. 3.8 - Complete this table for H2O:Ch. 3.8 - Prob. 26PCh. 3.8 - Complete this table for refrigerant-134a:Ch. 3.8 - A 1.8-m3 rigid tank contains steam at 220C....Ch. 3.8 - A pistoncylinder device contains 0.85 kg of...Ch. 3.8 - Prob. 30PCh. 3.8 -
3–31 10-kg of R-134a fill a 1.348-m3 rigid...Ch. 3.8 - Prob. 32PCh. 3.8 - Refrigerant-134a at 200 kPa and 25C flows through...Ch. 3.8 - Prob. 34PCh. 3.8 - The temperature in a pressure cooker during...Ch. 3.8 - Prob. 36PCh. 3.8 -
3–37E One pound-mass of water fills a 2.4264-ft3...Ch. 3.8 - Prob. 38PCh. 3.8 - Water is to be boiled at sea level in a...Ch. 3.8 - Repeat Prob. 340 for a location at an elevation of...Ch. 3.8 - 10 kg of R-134a at 300 kPa fills a rigid container...Ch. 3.8 - 100 kg of R-134a at 200 kPa are contained in a...Ch. 3.8 - Water initially at 200 kPa and 300C is contained...Ch. 3.8 -
3–44 Saturated steam coming off the turbine of a...Ch. 3.8 - Prob. 45PCh. 3.8 - Prob. 46PCh. 3.8 - Water is being heated in a vertical pistoncylinder...Ch. 3.8 - Prob. 49PCh. 3.8 - A rigid tank with a volume of 1.8 m3 contains 40...Ch. 3.8 - A pistoncylinder device contains 0.005 m3 of...Ch. 3.8 -
3–53E A 5-ft3 rigid tank contains 5 lbm of water...Ch. 3.8 - A 5-ft3 rigid tank contains a saturated mixture of...Ch. 3.8 - Superheated water vapor at 180 psia and 500F is...Ch. 3.8 - Prob. 57PCh. 3.8 - 3–58 A rigid tank contains water vapor at 250°C...Ch. 3.8 - A pistoncylinder device initially contains 1.4 kg...Ch. 3.8 - How much error would one expect in determining the...Ch. 3.8 - Prob. 61PCh. 3.8 -
3–62 A rigid vessel contains 8 kg of...Ch. 3.8 - A rigid tank initially contains 1.4 kg saturated...Ch. 3.8 - A pistoncylinder device initially contains 50 L of...Ch. 3.8 - Under what conditions is the ideal-gas assumption...Ch. 3.8 - Prob. 66PCh. 3.8 - Propane and methane are commonly used for heating...Ch. 3.8 - A 400-L rigid tank contains 5 kg of air at 25C....Ch. 3.8 - Prob. 69PCh. 3.8 - Prob. 70PCh. 3.8 - The pressure gage on a 2.5-m3 oxygen tank reads...Ch. 3.8 - A spherical balloon with a diameter of 9 m is...Ch. 3.8 - Reconsider Prob. 373. Using appropriate software,...Ch. 3.8 - Prob. 74PCh. 3.8 - Prob. 75PCh. 3.8 - A rigid tank whose volume is unknown is divided...Ch. 3.8 - Prob. 77PCh. 3.8 - Prob. 78PCh. 3.8 - Prob. 79PCh. 3.8 - Prob. 80PCh. 3.8 - Prob. 81PCh. 3.8 - Determine the specific volume of superheated water...Ch. 3.8 - Determine the specific volume of superheated water...Ch. 3.8 - Prob. 85PCh. 3.8 - Prob. 86PCh. 3.8 - Prob. 87PCh. 3.8 - Prob. 88PCh. 3.8 - Prob. 89PCh. 3.8 - Prob. 90PCh. 3.8 - Carbon dioxide gas enters a pipe at 3 MPa and 500...Ch. 3.8 - A 0.016773-m3 tank contains 1 kg of...Ch. 3.8 - What is the physical significance of the two...Ch. 3.8 - A 3.27-m3 tank contains 100 kg of nitrogen at 175...Ch. 3.8 - Prob. 95PCh. 3.8 - Refrigerant-134a at 400 psia has a specific volume...Ch. 3.8 - Nitrogen at 150 K has a specific volume of...Ch. 3.8 - A 1-m3 tank contains 2.841 kg of steam at 0.6 MPa....Ch. 3.8 - Prob. 102PCh. 3.8 - Prob. 103PCh. 3.8 - On a certain day, the temperature and relative...Ch. 3.8 - Prob. 105PCh. 3.8 - Consider two rooms that are identical except that...Ch. 3.8 - A thermos bottle is half-filled with water and is...Ch. 3.8 - Prob. 108RPCh. 3.8 - The combustion in a gasoline engine may be...Ch. 3.8 - A tank contains argon at 600C and 200 kPa gage....Ch. 3.8 - Prob. 111RPCh. 3.8 - Prob. 112RPCh. 3.8 - A rigid tank with a volume of 0.117 m3 contains 1...Ch. 3.8 - Prob. 114RPCh. 3.8 - Ethane at 10 MPa and 100C is heated at constant...Ch. 3.8 - Prob. 116RPCh. 3.8 - A 10-kg mass of superheated refrigerant-134a at...Ch. 3.8 - A 4-L rigid tank contains 2 kg of saturated...Ch. 3.8 - The gage pressure of an automobile tire is...Ch. 3.8 - Prob. 120RPCh. 3.8 - Steam at 400C has a specific volume of 0.02 m3/kg....Ch. 3.8 - A tank whose volume is unknown is divided into two...Ch. 3.8 - Prob. 123RPCh. 3.8 - Prob. 124RPCh. 3.8 - Prob. 125RPCh. 3.8 - A tank contains helium at 37C and 140 kPa gage....Ch. 3.8 - Prob. 127RPCh. 3.8 - Prob. 131RPCh. 3.8 - Consider an 18-m-diameter hot-air balloon that,...Ch. 3.8 - Prob. 134FEPCh. 3.8 - Water is boiled at 1 atm pressure in a coffeemaker...Ch. 3.8 - Prob. 136FEPCh. 3.8 - Prob. 137FEPCh. 3.8 - Water is boiled in a pan on a stove at sea level....Ch. 3.8 - Prob. 139FEPCh. 3.8 - Consider a sealed can that is filled with...Ch. 3.8 - A rigid tank contains 2 kg of an ideal gas at 4...Ch. 3.8 - The pressure of an automobile tire is measured to...
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- Problem 1 (65 pts, suggested time 50 mins). An elastic string of constant line tension1T is pinned at x = 0 and x = L. A constant distributed vertical force per unit length p(with units N/m) is applied to the string. Under this force, the string deflects by an amountv(x) from its undeformed (horizontal) state, as shown in the figure below.The PDE describing mechanical equilibrium for the string isddx Tdvdx− p = 0 . (1)(a) [5pts] Identify the BCs for the string and identify their type (essential/natural). Writedown the strong-form BVP for the string, including PDE and BCs.(b) [10pts] Find the analytical solution of the BVP in (a). Compute the exact deflectionof the midpoint v(L/2).(c) [15pts] Derive the weak-form BVP.(d) [5pts] What is the minimum number of linear elements necessary to compute the deflection of the midpoint?(e) [15pts] Write down the element stiffness matrix and the element force vector for eachelement.arrow_forwardProblem 1 (35 pts). An elastic string of constant line tension1 T is pinned at x = 0 andx = L. A constant distributed vertical force per unit length p (with units N/m) is appliedto the string. Under this force, the string deflects by an amount v(x) from its undeformed(horizontal) state, as shown in the figure below.Force equilibrium in the string requires thatdfdx − p = 0 , (1)where f(x) is the internal vertical force in the string, which is given byf = Tdvdx . (2)(a) [10pts] Write down the BVP (strong form) that the string deflection v(x) must satisfy.(b) [2pts] What order is the governing PDE in the BVP of (a)?(c) [3pts] Identify the type (essential/natural) of each boundary condition in (a).(d) [20pts] Find the analytical solution of the BVP in (a).arrow_forwardProblem 2 (25 pts, (suggested time 15 mins). An elastic string of line tension T andmass per unit length µ is pinned at x = 0 and x = L. The string is free to vibrate, and itsfirst vibration mode is shown below.In order to find the frequency of the first mode (or fundamental frequency), the string isdiscretized into a certain number of linear elements. The stiffness and mass matrices of thei-th element are, respectivelyESMi =TLi1 −1−1 1 EMMi =Liµ62 11 2 . (2)(a) [5pts] What is the minimum number of linear elements necessary to compute the fundamental frequency of the vibrating string?(b) [20pts] Assemble the global eigenvalue problem and find the fundamental frequency ofvibration of the stringarrow_forward
- I need part all parts please in detail (including f)arrow_forwardProblem 3 (10 pts, suggested time 5 mins). In class we considered the mutiphysics problem of thermal stresses in a rod. When using linear shape functions, we found that the stress in the rod is affected by unphysical oscillations like in the following plot E*(ux-a*T) 35000 30000 25000 20000 15000 10000 5000 -5000 -10000 0 Line Graph: E*(ux-a*T) MULT 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Arc length (a) [10pts] What is the origin of this issue and how can we fix it?arrow_forwardanswer the questions and explain all of it in words. Ignore where it says screencast and in class explanationarrow_forward
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