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Unformatted text preview: Chapter 1 Introduction and Overview Chapter 1 INTRODUCTION AND OVERVIEW Thermodynamics, Heat Transfer, and Fluid Mechanics 11C Classical thermodynamics is based on experimental observations whereas statistical thermodynamics is based on the average behavior of large groups of particles. 12C On a downhill road the potential energy of the bicyclist is being converted to kinetic energy, and thus the bicyclist picks up speed. There is no creation of energy, and thus no violation of the conservation of energy principle. 13C There is no truth to his claim. It violates the second law of thermodynamics. 14C Thermodynamics deals with the amount of heat transfer as a system undergoes a process from one equilibrium state to another. Heat transfer, on the other hand, deals with the rate of heat transfer as well as the temperature distribution within the system at a specified time. 15C The driving force is ( a ) the temperature difference for heat transfer, ( b ) the electric potential difference for electric current flow (voltage), and ( c ) the pressure difference for fluid flow. 16C Heat transfer is a nonequilibrium phenomena since in a system that is in equilibrium there can be no temperature differences and thus no heat flow. 17C No, there cannot be any heat transfer between two bodies that are at the same temperature (regardless of pressure) since the driving force for heat transfer is temperature difference. 18C Stress is defined as force per unit area, and is determined by dividing the force by the area upon which it acts. The normal component of a force acting on a surface per unit area is called the normal stress , and the tangential component of a force acting on a surface per unit area is called shear stress . In a fluid, the normal stress is called pressure . Mass, Force, and Units 19C Poundmass lbm is the mass unit in English system whereas poundforce lbf is the force unit. One poundforce is the force required to accelerate a mass of 32.174 lbm by 1 ft/s 2 . In other words, the weight of a 1lbm mass at sea level is 1 lbf. 110C Kg is the mass unit in the SI system whereas kgforce is a force unit. 1kgforce is the force required to accelerate a 1kg mass by 9.807 m/s 2 . In other words, the weight of 1kg mass at sea level is 1 kgforce. 111C There is no acceleration, thus the net force is zero in both cases. 112 A plastic tank is filled with water. The weight of the combined system is to be determined. Assumptions The density of water is constant throughout. Properties The density of water is given to be = 1000 kg/m 3 . Analysis The mass of the water in the tank and the total mass are m w = V = (1000 kg/m 3 )(0.2 m 3 ) = 200 kg m total = m w + m tank = 200 + 3 = 203 kg Thus, 11 m tank =3 kg V=0.2 m 3 H 2 O Chapter 1 Introduction and Overview N 1991 m/s kg 1 N 1 ) m/s kg)(9.807 (203 2 2 = = = mg W 113 The interior dimensions of a room are given. The mass and weight of the air in the room are to be The interior dimensions of a room are given....
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 Spring '08
 Chung
 Heat Transfer

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