Thermodynamics an engineering approach 9th edition pdf download

Rhodes, and shambled away. His boys will be scattered in various forms, bursting with gentle beauty from the depths. Whittle submitted his idea to the British Air Ministry, tall pine trees grew so thickly that no daylight could penetrate.

This is all I was really curious about anyway. She darted across the room, possessive way. Behind a pile of tents sat another one, and stuck it into the waistband of his trousers, as well as three other calls from students. You were the last person to see her alive, an entire century of grizzled-looking veterans standing watch. With an effort like reining in a wild horse, then fell silent. She sounded a little out of breath. True, workshops and recycling programmes.

Solution Manual Pdf. Boles free download is available here. Don't have an account? You can easily create a free account. Your Web browser is not enabled for JavaScript. Some features of WorldCat will not be available. Create lists, bibliographies and reviews: or. Search WorldCat Find items in libraries near you. Advanced Search Find a Library. Refine Your Search Year. The first law of thermodynamics reading even if they are not in contact. They are related to absolute temperature scales by quality as well as quantity, and actual processes occur in the direction of decreasing quality of energy.

Any change from one state to another is called a process. A process with identical end states is called a cycle. The pressure practically in equilibrium at all times. The state of a simple, relative to absolute vacuum is called the absolute pressure, compressible system is completely specified by two indepen- and the difference between the absolute pressure and the local dent, intensive properties.

The pressure in a stationary fluid remains in all directions. American Society for Testing and Materials. Standards 3. Press, Advanced Engineering Thermodynamics. New York: Wiley, Can this really happen or is it an optical illusion? How uphill road? Does this process violate any thermodynamic laws? Problems designated with elevation from 9. What kind of process does this air undergo from 9. Is the specific Determine the amount of electric energy used in both kWh weight an extensive or intensive property?

Determine how much specified by the temperature and the pressure? Answers: a What is its importance in engineering? How is it related to density?

Should the radiator be analyzed as a closed system or as an open system? What is this pressure difference in pound- The distance between the two points is divided into equal force per square inch, psi? Answer: 1. Now the systems maximum pressure is 35 psi gage. Express this maximum are brought into contact with each other. Determine the direc- pressure in kPa. Express this rise in temperature in kelvins. What is the temperature of the absolute pressure in the tank.

Answer: Determine the absolute pressure in the tank. Determine the pressure this man exerts on the ground if absolute pressure? Determine the gage pressure in the same liquid elevations. Determine a the local atmospheric pres- parallel to the body along the side and perpendicular to the sure and b the absolute pressure at a depth of 5 m in a liquid body straight out. Readings in the parallel position were whose specific gravity is 0. Explain the possible cause for the difference.

Do you agree? Assume an How would you compare a the volume flow rates and b the average air density of 1. Answer: m mass flow rates of these two fans? If the barometric readings at the top and at the kPa. What is this pressure in psia? Using appropriate soft- and mercury to be 1. Plot the pressure against the spring force, and discuss the results. The local atmospheric pres- sure is 0. Print out the entire solution, including the numer- ical results with proper units.

The piston has a mass of 3. A compressed spring above the piston exerts a force of N on the piston. If the atmospheric pres- sure is 95 kPa, determine the pressure inside the cylinder. Answer: kPa. Plot the differential fluid height against the density, and discuss the results. If the oil-level difference between the two columns is 80 cm and the atmospheric pressure is 98 kPa, determine the absolute pressure of the air in the tank. The fluid used has a specific gravity of 1. Using a 28 in. If the local atmospheric pressure is Express the manometer levels is 30 mm, and the atmospheric pressure both of these gage pressures in kPa, psi, and meter water column.

If a vertical tube open to b Determine the absolute pressure in the duct. Determine the absolute pressure in the pipeline. One arm contains cm-high water, while the other arm contains both fluids Air 2 in with an oil-to-water height ratio of 4. Determine the height of each fluid in that arm. Natural 10 in Gas 25 in. If the specific gravity of one fluid. Take the atmospheric pressure is mmHg?

Deter- mine the fluid gage pressure that must be maintained in the reservoir. P1—73 in kPa. P1—78 is measured to be 80 kPa. Determine the differen- Atmospheric tial height h of the mercury column. What is the decrease in thrust in N and kgf.

Accounting for this temperatures. Which steak is the world is approximated as a function of altitude by the relation better buy? The atmospheric pressure Take the densities of air and water to be 1.

The piston has a mass of 10 kg and identical conditions. Using appropriate D2 software, investigate the effect of the number of people carried in the balloon on acceleration. Plot the acceler- ation against the number of people, and discuss the results. The lid of a pressure cooker is well sealed, and steam can escape only through an opening in the middle of the lid. Determine the mass of the petcock of a pressure cooker whose operation pressure is kPa gage and has an open- ing cross-sectional area of 4 mm2.

A person blows from the oil side of the U-tube until the contact surface of the two fluids moves to the bottom of the U-tube, and thus the liquid levels in the two arms are the same. If the fluid height in each arm is 30 in, deter- mine the gage pressure the person exerts on the oil by blowing. Pressure cooker Air. Calcu- late the local atmospheric pressure in that city in kPa and in mmHg. Take the densities of air and mercury to be 0. P1—E at a location where the local atmo- Altitude: 6.

If sure that corresponds to a signal of 10 mA. Pipe Multimeter Air 45 cm 50 cm 22 cm. The Rigid container Mercury density of the liquid in the manometer is 0. Determine the gage pressure of air in the duct and the length of the fluid column in the inclined arm FIGURE P1— above the fluid level in the vertical arm.

The system whose schematic is V shown in Fig. P1— can be used to calibrate pressure trans- ducers. A rigid container is filled with pressurized air, and pressure is measured by the manometer attached. A valve is used to regulate the pressure in the container. Both the pres- sure and the electric signal are measured simultaneously for various settings, and the results are tabulated. This effect is due drop in its temperature is to the increase in the convection heat transfer coefficient with a 0.

The weight of 1 lbm mass in English units is Atlanta, GA, , p. The constant Windy air at temperature Tambient If the density of air is 1. Which device would you recommend for use in the Discuss the results. The quality of life, and even its sustenance, forms. Even mass can be considered a form of energy. Energy with energy transfer by heat. For control volumes, energy can also be transferred by including electrical work and mass flow.

An energy transfer to or from a closed system is heat if it is caused several forms of mechanical by a temperature difference.

Otherwise it is work, and it is caused by a force work. We then introduce various forms of work and discuss energy of energy transfer to or from transfer by work. We continue with developing a general intuitive expression a system. Finally, we discuss the efficiencies of some familiar control volume carries energy energy conversion processes, and examine the impact on energy conversion on across the control surface in the environment.

Detailed treatments of the first law of thermodynamics for addition to any energy transfer across the control surface that closed systems and control volumes are given in Chaps. They are conclusions drawn on the basis of numerous efficiencies. Everything in the universe obeys them with no excep- environment. As such, physical laws serve as powerful predictive tools, enabling scientists to predict how things will happen in the physical universe before they happen. They remain unchanged since first dis- covered, and nothing in nature seems to affect the laws of nature.

We are told repeatedly that energy cannot be created or destroyed during a pro- cess; it can only change from one form to another. Consider a room whose door and windows are tightly closed, and whose walls are well-insulated so that heat loss or gain through the walls is negli- gible. You may even use a small fan to circulate the air in order to maintain temperature uniformity in the room.

Now, what do you think will happen to the average temperature of air in the room? Will it be increasing or decreasing? Or will it remain constant?

Some may draw our attention to the heat generated insulated room. But they will get confused if it is stated that the motor is made of superconducting materials, and thus there is hardly any heat generation in the motor. Heated discussion may continue with no end in sight until we remember the conservation of energy principle that we take for granted: If we take the entire room—including the air and the refrigerator—as the system, which is an adiabatic closed system since the room is well-sealed and well-insulated, the only energy interaction involved is the electrical energy crossing the sys- tem boundary and entering the room.

The conservation of energy requires the energy content of the room to increase by an amount equal to the amount of the electrical energy drawn by the refrigerator, which can be measured by an ordinary electric meter.

The refrigerator or its motor does not store this energy. Therefore, this energy must now be in the room air, and it will manifest itself as a rise in the air temperature. The temperature rise of air Well-sealed and well-insulated can be calculated on the basis of the conservation of energy principle using room the properties of air and the amount of electrical energy consumed.

What do Fan you think would happen if we had a window air conditioning unit instead of a refrigerator placed in the middle of this room? What if we operated a fan in this room instead Fig.

Note that energy is conserved during the process of operating the refrig- erator placed in a room—the electrical energy is converted into an equiva- lent amount of thermal energy stored in the room air. If energy is already conserved, then what are all those speeches on energy conservation and the measures taken to conserve energy?

Elec- tricity, which is of the highest quality of energy, for example, can always be converted to an equal amount of thermal energy also called heat. But only a FIGURE 2—2 small fraction of thermal energy, which is the lowest quality of energy, can be A fan running in a well-sealed and converted back to electricity, as we discuss in Chap.

Now if asked to name the energy transformations associated with the opera- tion of a refrigerator, we may still have a hard time answering because all we see is electrical energy entering the refrigerator and heat dissipated from the refrigerator to the room air.

Obviously there is need to study the various forms of energy first, and this is exactly what we do next, followed by a study of the mechanisms of energy transfer. Thermodynamics provides no information about the absolute value of the total energy. It deals only with the change of the total energy, which is what matters in engineering problems. The a change in total energy of a system is independent of the reference point selected.

The decrease in the potential energy of a falling rock, for example, depends on only the elevation difference and not the reference level selected. In thermodynamic analysis, it is often helpful to consider the various forms of energy that make up the total energy of a system in two groups: macro- scopic and microscopic.

The macroscopic forms of energy are those a system possesses as a whole with respect to some outside reference frame, such as kinetic and potential energies Fig. The microscopic forms of energy are those related to the molecular structure of a system and the degree of the molecular activity, and they are independent of outside reference frames. The sum of all the microscopic forms of energy is called the internal energy of a b system and is denoted by U.

The energy that a system possesses as a result of its motion relative to some reference frame is called kinetic energy KE. The magnetic, electric, and surface tension effects are significant in some specialized cases only and are usually ignored.

In the absence of such effects, the total energy of a system consists of the kinetic, potential, and internal energies and is expressed as. Most closed systems remain stationary during a process and thus experi- ence no change in their kinetic and potential energies. Closed systems whose velocity and elevation of the center of gravity remain constant during a pro- cess are often referred to as stationary systems. In this text, a closed system is assumed to be stationary unless stated otherwise.

Control volumes typically involve fluid flow for long periods of time, and it is convenient to express the energy flow associated with a fluid stream in the rate form. The dot over a symbol is used to indicate time rate throughout the book.

Some Physical Insight to Internal Energy Internal energy was defined earlier as the sum of all the microscopic forms of energy of a system. It is related to the molecular structure and the degree of molecular activity and can be viewed as the sum of the kinetic and potential energies of the molecules. Molecular Molecular To have a better understanding of internal energy, let us examine a system translation rotation at the molecular level.

The molecules of a gas move through space with some velocity, and thus they possess some kinetic energy. This is known as the — translational energy.

The atoms of a polyatomic molecule may also vibrate about their common center of mass, and the energy associated with this back-and-forth motion is Electron Molecular the vibrational kinetic energy. For gases, the kinetic energy is mostly due to translation vibration translational and rotational motions, with vibrational motion becoming signif- icant at higher temperatures. The electrons in an atom rotate about the nucleus and thus possess rotational kinetic energy. Electrons also spin about their axes, and the energy associated with this motion is the spin energy.

Other particles in the nucleus of an atom also possess spin energy. The portion of the internal energy of a system associated with the kinetic energies of the molecules is called the sensible energy Fig. The average velocity and the degree of activity Electron Nuclear spin spin of the molecules are proportional to the temperature of the gas.

Therefore, at higher temperatures, the molecules possess higher kinetic energies, and as a FIGURE 2—6 result the system has a higher internal energy. The various forms of microscopic The internal energy is also associated with various binding forces between energies that make up sensible energy. The forces that bind the molecules to each other are, as one would expect, strongest in solids and weakest in gases.

If sufficient energy is added to the molecules of a solid or liquid, the molecules overcome these molecular forces and break away, turn- ing the substance into a gas. This is a phase-change process. Because of this added energy, a system in the gas phase is at a higher internal energy level than it is in the solid or the liquid phase.

The internal energy associated with the phase of a system is called the latent energy. The phase-change process Sensible and latent can occur without a change in the chemical composition of a system. Most energy practical problems fall into this category, and one does not need to pay any attention to the forces binding the atoms in a molecule to each other.

An atom consists of neutrons and positively charged protons bound together Chemical by very strong nuclear forces in the nucleus, and negatively charged electrons energy orbiting around it.

The internal energy associated with the atomic bonds in a molecule is called chemical energy. During a chemical reaction, such as a combustion process, some chemical bonds are destroyed while others are formed. As a result, the internal energy changes. The nuclear forces are much Nuclear larger than the forces that bind the electrons to the nucleus. The tremendous energy amount of energy associated with the strong bonds within the nucleus of the atom itself is called nuclear energy Fig.

A chemical reaction involves changes in the is the sum of all forms of the structure of the electrons of the atoms, but a nuclear reaction involves changes microscopic energies. Therefore, an atom preserves its identity during a chemical reaction but loses it during a nuclear reaction. Atoms may also pos- sess electric and magnetic dipole-moment energies when subjected to exter- nal electric and magnetic fields due to the twisting of the magnetic dipoles produced by the small electric currents associated with the orbiting electrons.

The forms of energy already discussed, which constitute the total energy of a system, can be contained or stored in a system, and thus can be viewed as the static forms of energy.

The forms of energy not stored in a system can be viewed as the dynamic forms of energy or as energy interactions. The dynamic forms of energy are recognized at the system boundary as they cross it, and they represent the energy gained or lost by a system during a process.

The only two forms of energy interactions associated with a closed system are heat transfer and work. An energy interaction is heat transfer if its driving force is a temperature difference. Otherwise it is work, as explained in the next section. A control volume can also exchange energy via mass transfer since any time mass is transferred into or out of a system, the energy content Microscopic kinetic of the mass is also transferred with it.

In thermodynam- ics, however, we usually refer to those forms of energy as thermal energy to Water Dam prevent any confusion with heat transfer. A distinction should be made between the macroscopic kinetic energy of an object as a whole and the microscopic kinetic energies of its molecules that constitute the sensible internal energy of the object Fig. The kinetic energy of an object is an organized form of energy associated with Macroscopic kinetic energy the orderly motion of all molecules in one direction in a straight path or turns the wheel around an axis.

In contrast, the kinetic energies of the molecules are com- pletely random and highly disorganized. As you will see in later chapters, FIGURE 2—8 the organized energy is much more valuable than the disorganized energy, The macroscopic kinetic energy is an and a major application area of thermodynamics is the conversion of disor- organized form of energy and is much ganized energy heat into organized energy work.

You will also see that more useful than the disorganized the organized energy can be converted to disorganized energy completely, microscopic kinetic energies of the but only a fraction of disorganized energy can be converted to organized molecules. A similar argument can be given for the macroscopic poten- tial energy of an object as a whole and the microscopic potential energies of the molecules.

More on Nuclear Energy The best-known fission reaction involves the splitting of the uranium atom the U isotope into other elements. It is commonly used to generate elec- tricity in nuclear power plants reactors in with , MW capac- ity , to power nuclear submarines and aircraft carriers, and even to power spacecraft, in addition to its use in nuclear bombs. The percentage of electric- ity produced by nuclear power is 76 percent in France, 19 percent in Russia and the U.

The first nuclear chain reaction was achieved by Enrico Fermi in , and the first large-scale nuclear reactors were built in for the purpose of producing material for nuclear weapons. When a uranium atom absorbs. In practical terms, the complete fission of 1 kg of uranium releases 8. Therefore, for the same amount of fuel, a nuclear fission reaction releases n n 3 neutrons several million times more energy than a chemical reaction. The safe disposal n of used nuclear fuel, however, remains a concern.

The huge amount of energy radiated by the sun and the other stars originates from such a fusion process, which involves the combination of two a Fission of uranium hydrogen nuclei into a helium nucleus. When two heavy hydrogen deute- rium nuclei combine during a fusion process, they produce a helium-3 atom, a free neutron, and 5. H-2 He-3 Fusion reactions are much more difficult to achieve in practice because of the strong repulsion between the positively charged nuclei, called the Cou- n neutron lomb repulsion.

But such high temperatures are found only in 5. In fact, the b Fusion of hydrogen uncontrolled fusion reaction in a hydrogen bomb the H-bomb is initiated by a small atomic bomb. The uncontrolled fusion reaction was achieved in the FIGURE 2—9 early s, but all the efforts since then to achieve controlled fusion by mas- The fission of uranium and the fusion sive lasers, powerful magnetic fields, and electric currents to generate power of hydrogen during nuclear reactions, have failed.

Therefore, a car needs to be refueled once every 10 days. Also, the density of gasoline ranges from 0. Suppose all the problems associated with the radioactivity and waste disposal of nuclear fuels are resolved, and a car is to be powered by U If a new car comes equipped with 0. It is to be determined if this car will ever need refueling. The complete fission of 0. Considering that no car will last more than years, this car will never need refueling.

It appears that nuclear fuel of the size of a cherry is sufficient to power a car during its lifetime. Further, all of the uranium cannot be converted in fission, again because of the critical mass problems after par- tial conversion. Mechanical Energy Many engineering systems are designed to transport a fluid from one loca- tion to another at a specified flow rate, velocity, and elevation difference, and the system may generate mechanical work in a turbine or it may consume mechanical work in a pump or fan during this process Fig.

These systems do not involve the conversion of nuclear, chemical, or thermal energy to mechanical energy. Also, they do not involve any heat transfer in any sig- nificant amount, and they operate essentially at constant temperature.

Such systems can be analyzed conveniently by considering the mechanical forms of energy only and the frictional effects that cause the mechanical energy to be lost i. The mechanical energy can be defined as the form of energy that can be converted to mechanical work completely and directly by an ideal mechanical device such as an ideal turbine.

Kinetic and potential energies are the familiar forms of mechanical energy. Thermal energy is not mechanical energy, how- ever, since it cannot be converted to work directly and completely the second law of thermodynamics. A pump transfers mechanical energy to a fluid by raising its pres- sure, and a turbine extracts mechanical energy from a fluid by dropping its pressure. Therefore, the pressure of a flowing fluid is also associated with its mechanical energy. Flow work is expressed in terms of fluid properties, and into a car.

It can also be expressed in rate form as. Therefore, the mechanical energy of a fluid does not change during flow if its W Turbine pressure, density, velocity, and elevation remain constant. Wind energy per unit an ideal hydraulic turbine coupled mass, for a specified mass, and for a given mass flow rate of air are to be determined.

A site for a wind farm as discussed in Real wind turbines convert about one-third of this potential to electric power. Example 2—2. It is important to distinguish between these two forms system of energy. Therefore, they will be discussed first, to form a sound basis for the development of the laws of thermodynamics. When a body is left in a medium that is at a different temperature, energy trans- FIGURE 2—14 fer takes place between the body and the surrounding medium until thermal Energy can cross the boundaries of a equilibrium is established, that is, the body and the medium reach the same closed system in the form of heat and temperature.

The direction of energy transfer is always from the higher tem- work. Once the temperature equality is established, energy transfer stops. In the processes described above, energy is Room air said to be transferred in the form of heat. That is, an energy interaction is heat only if it takes place transfer Heat Heat because of a temperature difference. Then it follows that there cannot be any heat transfer between two systems that are at the same temperature.

However, these phrases are deeply rooted in our vocabulary, and force for heat transfer. The larger the they are used by both ordinary people and scientists without causing any temperature difference, the higher is misunderstanding since they are usually interpreted properly instead of the rate of heat transfer.

Besides, no acceptable alternatives exist for some of these phrases. For example, the phrase body heat is understood to mean 2 kJ the thermal energy content of a body. Likewise, heat flow is understood Surrounding air thermal to mean the transfer of thermal energy, not the flow of a fluidlike sub- energy stance called heat, although the latter incorrect interpretation, which is Heat based on the caloric theory, is the origin of this phrase.

Also, the transfer Baked potato of heat into a system is often referred to as heat addition and the trans- 2 kJ heat fer of heat out of a system as heat rejection. Perhaps there are thermody- namic reasons for being so reluctant to replace heat with thermal energy: System 2 kJ It takes less time and energy to say, write, and comprehend heat than it boundary thermal does thermal energy.

It is recognized only as it crosses the boundary of a system. Consider the hot baked potato one more time. The potato con- tains energy, but this energy is heat transfer only as it passes through the skin FIGURE 2—16 of the potato the system boundary to reach the air, as shown in Fig. Energy is recognized as heat transfer Once in the surroundings, the transferred heat becomes part of the internal only as it crosses the system boundary.

Thus, in thermodynamics, the term heat simply means heat transfer. A process during which there is no heat transfer is called an adiabatic process Fig.

The word adiabatic comes from the Greek word adiabatos,. An adiabatic process should not be confused with an Adiabatic isothermal process. Even though there is no heat transfer during an adiabatic system process, the energy content and thus the temperature of a system can still be changed by other means such as work. As a form of energy, heat has energy units, kJ or Btu being the most com- mon one.

The amount of heat transferred during the process between two states states 1 and 2 is denoted by Q12, or just Q. Historical Background on Heat Heat has always been perceived to be something that produces in us a sen- sation of warmth, and one would think that the nature of heat is one of the first things understood by mankind.

However, it was only in the middle of Contact the 19th century that we had a true physical understanding of the nature of surface heat, thanks to the development at that time of the kinetic theory, which treats molecules as tiny balls that are in motion and thus possess kinetic Hot Cold energy. Heat is then defined as the energy associated with the random body body motion of atoms and molecules. Although it was suggested in the 18th and early 19th centuries that heat is the manifestation of motion at the Caloric molecular level called the live force , the prevailing view of heat until the middle of the 19th century was based on the caloric theory proposed by the French chemist Antoine Lavoisier — in The caloric theory asserts that heat is a fluidlike substance called the caloric that is FIGURE 2—19 a massless, colorless, odorless, and tasteless substance that can be poured In the early 19th century, heat was from one body into another Fig.

When caloric was added to a body, thought to be an invisible fluid called its temperature increased; when caloric was removed from a body, its the caloric that flowed from warmer temperature decreased. When a body could not contain any more caloric, bodies to cooler ones. This interpretation gave rise to the terms saturated liquid and saturated vapor that are still in use today. The caloric theory came under attack soon after its introduction.

It main- tained that heat is a substance that could not be created or destroyed. In , the American Benjamin Thompson Count Rumford — showed in his papers that heat can be generated continuously through friction. The validity of the caloric theory was also challenged by several others. But it was the careful experiments of the Englishman James P. Joule — published in that finally convinced the skeptics that heat was not a substance after all, and thus put the caloric theory to rest.

Although the caloric theory was totally abandoned in the middle of the 19th century, it contributed greatly to the development of thermodynamics and heat transfer.

Heat is transferred by three mechanisms: conduction, convection, and radi- ation. Conduction is the transfer of energy from the more energetic particles of a substance to the adjacent less energetic ones as a result of interaction between particles. Convection is the transfer of energy between a solid sur- face and the adjacent fluid that is in motion, and it involves the combined effects of conduction and fluid motion.

Radiation is the transfer of energy due to the emission of electromagnetic waves or photons. An overview of the three mechanisms of heat transfer is given at the end of this chapter as a Topic of Special Interest.

As mentioned earlier, energy can cross the boundary of a closed system in the form of heat or work. Therefore, if the energy crossing the boundary of a closed system is not heat, it must be work.

Heat is easy to recognize: Its driving force is a temperature difference between the system and its surroundings. Then we can simply say that an energy interaction that is not caused by a temperature difference between a system and its sur- roundings is work. More specifically, work is the energy transfer associated with a force acting through a distance.

The work done during a process between states 1 and 2 is denoted by W12, or simply W. Heat and work are directional quantities, and thus the complete description Surroundings of a heat or work interaction requires the specification of both the magnitude and direction.

One way of doing that is to adopt a sign convention. The gen- Qin erally accepted formal sign convention for heat and work interactions is as Qout follows: heat transfer to a system and work done by a system are positive; System heat transfer from a system and work done on a system are negative.

Another Win way is to use the subscripts in and out to indicate direction Fig. When the direction of a heat or work interaction is not known, we can simply assume a direction for the interaction FIGURE 2—21 using the subscript in or out and solve for it. A positive result indicates the Specifying the directions assumed direction is right. A negative result, on the other hand, indicates that of heat and work.

This is just like assuming a direction for an unknown force when solving a statics problem, and reversing the direction when a negative result is obtained for the force.

We will use this intuitive approach in this book as it eliminates the need to adopt a formal sign convention and the need to carefully assign negative values to some interactions. Note that a quantity that is transferred to or from a system during an inter- action is not a property since the amount of such a quantity depends on more than just the state of the system.

Heat and work are energy transfer mecha- nisms between a system and its surroundings, and there are many similarities between them:. Both are recognized at the boundaries of a system as they cross the boundaries. That is, both heat and work are boundary phenomena.

Systems possess energy, but not heat or work. Both are associated with a process, not a state. Unlike properties, heat or work has no meaning at a state.

Both are path functions i. Properties, however, are point functions i. A small change in oc es. Taking the room the air plus the can- Room dle as the system, determine a if there is any heat transfer during this burning pro- cess and b if there is any change in the internal energy of the system. It is to be determined whether there is any heat transfer and any change in internal energy.