Midterm22007

# Midterm22007 - ENGR 225 October 31, 2007 Name _ Please...

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ENGR 225 Name ___________________________ October 31, 2007 Please Check One Recitation: 8:30___;10:15; ___1:15___ Short answer (2 pts. Each, for T/F and multiple choice circle the best answer of the choices given , fill in the blank must be completed with a meaningful word or phrase) 1. For flow in a pipe, the mass flow rate is the product of the density of the fluid, the cross sectional area perpendicular to the direction of flow and the ______________ velocity of the fluid. 2. T F For steady state flow, ˙ m in " = ˙ m out " is always true. 3. Flow work a) is the same as flow energy b) is the product of pressure and volume c) has the same units as kinetic energy d) all of the above e) none of the above 4. For an open system, energy can be transported into and out of the system by both of the mechanisms that operate for closed systems. In addition , for open systems _______________ can transfer energy in or out. 5. T F The expression, ˙ Q " ˙ W = ˙ m out # h + V 2 2 + gz \$ % ( ) " ˙ m in # h + V 2 2 + gz \$ % ( ) is the first law of thermodynamics applied to steady flow through an open system. 6. For flow through an adiabatic throttling valve as illustrated to the right, the energy balance given in question 5 simplifies to a) ˙ Q = ˙ W b) ˙ m 1 h 1 + V 1 2 2 " # \$ % = ˙ m 2 h 2 + V 2 2 2 " # \$ % c) h 1 = h 2 d) none of the above 7. A turbine ______________ energy from moving fluid. 8. T F When a process is cyclic, the cycle is closed only when the fluid returns to its original state. 9. All heat engines in the real world a) move energy from a low temperature source to a high temperature sink b) reject heat to the surroundings c) require η th >1 d) can be run backwards 10. A refrigerator requires the input of energy in the form of _____________ to operate. 11. T F Compressed air engines (like the one demonstrated in class) operate on a cycle. 12. The second law of thermodynamics can be stated as a) it is impossible for any device that operates on a cycle to receive heat from a single reservoir and produce a net amount of work b) it is impossible to construct a device that operates in a cycle and produces no effect other than the transfer of heat from a lower-temperature body to a higher-temperature body

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## This test prep was uploaded on 04/08/2008 for the course ENGR 225 taught by Professor Landau during the Fall '08 term at Case Western.

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Midterm22007 - ENGR 225 October 31, 2007 Name _ Please...

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