Questions and Answers of Fundamentals Of Thermodynamics

A piston/cylinder has a water volume separated in VA = 0.2 m3 and VB = 0.3 m3 by a stiff membrane (Fig. P3.211). The initial state in A is 1000 kPa, x = 0.75 and in B it is 1600 kPa and 250◦C.
A sheet of rubber is stretched out over a ring of radius 0.25 m. I pour liquid water at 20◦C on it, as in Fig. P3.205, so that the rubber forms a half sphere (cup). Neglect the rubber mass and find
A film of ethanol at 20◦C has a surface tension of 22.3 mN/m and is maintained on a wire frame, as shown in Fig. P3.202. Consider the film with two surfaces as a control mass and find the work done
The piston/cylinder arrangement in Fig. P3.181 contains 10 g ammonia at 20◦C with a volume of 1 L. There are some stops, so if the piston is at the stops, the volume is 1.4 L. The ammonia is now
Consider the pot in Problem 3.119. Assume the stove supplies 1 kW of heat. How much time does the process take?Data from Problem 3.119.A 1-kg steel pot contains 1 kg liquid water, both at 15◦C. The
A steam-generating unit heats saturated liquid water at constant pressure of 800 kPa in a piston/ cylinder device. If 1.5 kW of power is added by heat transfer, find the rate (kg/s) at which
A 1.2-kg pot of water at 20◦C is put on a stove supplying 250Wto the water. How long will it take to come to a boil (100◦C)?
As fresh-poured concrete hardens, the chemical transformation releases energy at a rate of 2 W/kg. Assume that the center of a poured layer does not have any heat loss and that it has an average heat
A pot of water is boiling on a stove supplying 325W to the water. What is the rate of mass (kg/s) vaporization, assuming a constant pressure process?
A piston/cylinder of cross-sectional area 0.01 m2 maintains constant pressure. It contains 1 kg of water with a quality of 5% at 150◦C. If we heat the water so that 1 g/s of liquid turns into
Air in a rigid tank is at 100 kPa, 300 K with a volume of 0.75m3. The tank is heated to 400 K, state 2. Now one side of the tank acts as a piston, letting the air expand slowly at constant
A piston/cylinder has 0.5 kg of air at 2000 kPa, 1000 K, as shown in Fig. P3.183. The cylinder has stops, so Vmin=0.03m3. The air now cools to 400K by heat transfer to the ambient. Find the final
Air in a piston/cylinder assembly at 200 kPa and 600 K is expanded in a constant-pressure process to twice the initial volume, state 2, as shown in Fig. P3.182. The piston is then locked with a pin,
The piston/cylinder in Fig. P3.179 contains 0.1 kg R-410a at 600 kPa, 60◦C. It is now cooled, so the volume is reduced to half of the initial volume. The piston has upper stops mounted, and the
Water in a piston/cylinder (Fig. P3.174) is at 101 kPa, 25◦C, and mass 0.5 kg. The piston rests on some stops, and the pressure should be 1000 kPa to float the piston. We now heat the water, so the
A vertical cylinder fitted with a piston contains 5 kg of R-410a at 10◦C, as shown in Fig. P3.173. Heat is transferred to the system, causing the piston to rise until it reaches a set of stops, at
A helium gas is heated at constant volume from 100 kPa, 300 K to 500 K. A following process expands the gas at constant pressure to three times the initial volume. What is the specific work and the
Ten kilograms of water in a piston/cylinder arrangement exists as saturated liquid/vapor at 100 kPa, with a quality of 50%. The system is now heated so that the volume triples. The mass of the piston
A piston/cylinder shown in Fig. P3.169 contains 0.5 m3 of R-410a at 2 MPa, 150◦C. The piston mass and atmosphere give a pressure of 450 kPa that will float the piston. The whole setup cools in a
A piston/cylinder contains pure oxygen at 500 K, 600 kPa. The piston is moved to a volume such that the final temperature is 700 K in a polytropic process with exponent n = 1.25. Use ideal gas
Nitrogen gas goes through a polytropic process with n = 1.3 in a piston/cylinder arrangement. It starts out at 600 K, 600 kPa and ends at 800 K. Find the final pressure, the process specific work and
Air goes through a polytropic process with n = 1.3 in a piston/cylinder setup. It starts at 200 kPa, 300 K and ends with a pressure of 2200 kPa. Find the expansion ratio v2/v1, the specific work, and
An air pistol contains compressed air in a small cylinder, as shown in Fig. P3.164. Assume that the volume is 1 cm3, the pressure is 1MPa, and the temperature is 27◦C when armed. A bullet, with m =
A piston/cylinder assembly in a car contains 0.2 L of air at 90 kPa and 20◦C, as shown in Fig. P3.163. The air is compressed in a quasi-equilibrium polytropic process with polytropic exponent n =
A piston/cylinder contains pure oxygen at ambient conditions 20◦C, 100 kPa. The piston is moved to a volume that is seven times smaller than the initial volume in a polytropic process with exponent
A piston/cylinder arrangement of initial volume 0.025 m3 contains saturated water vapor at 180◦C. The steam now expands in a polytropic process with exponent n = 1 to a final pressure of 200 kPa
A piston/cylinder device contains 0.1 kg of air at 300 K and 100 kPa. The air is now slowly compressed in an isothermal (T = constant) process to a final pressure of 250 kPa. Show the process in a
Air in a piston/cylinder is at 1800 K, 7 MPa and expands in a polytropic process with n = 1.5 to a volume eight times larger. Find the specific work and specific heat transfer in the process and draw
A constant-pressure piston/cylinder contains 0.5 kg air at 300 K, 400 kPa. Assume the piston/ cylinder has a total mass of 1 kg steel and is at the same temperature as the air at any time. The system
A spring-loaded piston/cylinder contains 1.5 kg of air at 27◦C and 160 kPa. It is now heated to 900Kin a process wherein the pressure is linear in volume to a final volume of twice the initial
A 10-m-high cylinder, with a cross-sectional area of 0.1 m2, has a massless piston at the bottom with water at 20◦C on top of it, as shown in Fig. P3.145. Air at 300 K, with a volume of 0.3 m3,
A closed rigid container is filled with 1.5 kg water at 100 kPa, 55◦C; 1 kg of stainless steel, and 0.5 kg of polyvinyl chloride, both at 20◦C, and 0.1 kg air at 400 K, 100 kPa. It is now left
The temperature of water at 400 kPa is raised from 150◦C to 1200◦C. Evaluate the change in specific internal energy using (a) The steam tables, (b) The ideal gas Table A.8, and (c)
An engine, shown in Fig. P3.126, consists of a 100-kg cast iron block with a 20-kg aluminum head, 20 kg of steel parts, 5 kg of engine oil, and 6 kg of glycerine (antifreeze). All initial
A piston/cylinder (0.5 kg steel altogether) maintaining a constant pressure has 0.2 kg R-134a as saturated vapor at 150 kPa. It is heated to 40◦C, and the steel is at the same temperature as the
A copper block of volume 1 L is heat treated at 500◦C and now cooled in a 200-L oil bath initially at 20◦C, as shown in Fig. P3.118. Assuming no heat transfer with the surroundings, what is the
A computer CPU chip consists of 50 g silicon, 20 g copper, and 50 g polyvinyl chloride (plastic). It now heats from 15◦C to 70◦C as the computer is turned on. How much energy did the heating
In a sink, 5 L of water at 70◦C is combined with 1 kg of aluminum pots, 1 kg of silverware (steel), and 1 kg of glass, all put in at 20◦C. What is the final uniform temperature, neglecting any
A piston/cylinder contains 1.5 kg water at 600 kPa, 350◦C. It is now cooled in a process wherein pressure is linearly related to volume to a state of 200 kPa, 150◦C. Plot the P–v diagram for
The piston/cylinder in Fig. P3.111 contains 0.1 kg water at 500◦C, 1000 kPa. The piston has a stop at half of the original volume. The water now cools to a room temperature of 25◦C. a.
A rigid steel tank of mass 2.5 kg contains 0.5 kg R410a at 0◦C with a specific volume of 0.01m3/kg. The whole system is now heated to a room temperature of 25◦C.a. Find the volume of the tank.b.
A piston/cylinder contains carbon dioxide at −20◦C and quality 75%. It is compressed in a process wherein pressure is linear in volume to a state of 3 MPa and 20◦C. Find specific heat transfer.
A 10-m-high open cylinder, with Acyl = 0.1 m2, contains 20◦C water above and 2 kg of 20◦C water below a 198.5-kg thin insulated floating piston, as shown in Fig. P3.107. Assume standard g, P0.
A piston/cylinder arrangement with a linear spring similar to Fig. P3.105 contains R-134a at 15◦C, x= 0.4 and a volume of 0.02m3. It is heated to 60◦C, at which point the specific volume is 0.030
A cylinder having a piston restrained by a linear spring (of spring constant 15 kN/m) contains 0.5 kg of saturated vapor water at 120◦C, as shown in Fig. P3.105. Heat is transferred to the water,
A25-kg mass moves at 25 m/s. Now a brake system brings the mass to a complete stop with a constant deceleration over a period of 5 s. Assume the mass is at constant P and T. The brake energy is
Give the phase and the specific volume for the following:a. R-410a, T =−25 F, P = 30 lbf/in.2b. R-410a, T =−25 F, P = 40 lbf/in.2c. H2O, T = 280 F, P = 35 lbf/in.2d. NH3, T = 60 F, P = 15 lbf/in.2
Air in a spring-loaded piston/cylinder setup has a pressure that is linear with volume, P = A + BV. With an initial state of P = 150 kPa, V = 1 L and a final state of 800 kPa, V = 1.5 L, it is
Heat transfer to a 1.5-kg block of ice at −10◦C melts it to liquid at 10◦C in a kitchen. How much work does the water gives out?
A piston/cylinder contains 2 kg of water at 20◦C with a volume of 0.1m3. By mistake someone locks the piston, preventing it from moving while we heat the water to saturated vapor. Find the final
A nitrogen gas goes through a polytropic process with n = 1.3 in a piston/cylinder. It starts out at 600 K, 600 kPa and ends at 800 K. Is the work positive, negative, or zero?
Aballoon behaves so that the pressure isP=C2V1/3 and C2 = 100 kPa/m. The balloon is blown up with air from a starting volume of 1 m3 to a volume of 4 m3. Find the final mass of air, assuming it is at
Consider a piston/cylinder setup with 0.5 kg of R-134a as saturated vapor at−10◦C. It is now compressed to a pressure of 500 kPa in a polytropic process with n = 1.5. Find the final volume and
A water heater is covered with insulation boards over a total surface area of 3 m2. The inside board surface is at 75◦C, the outside surface is at 18◦C, and the board material has a conductivity
A steel pot, with conductivity of 50 W/m K and a 5-mm-thick bottom, is filled with 15◦Cliquidwater. The pot has a diameter of 20 cm and is now placed on an electric stove that delivers 500 W as
Determine the phase of the following substances and find the values of the unknown quantities.a. Nitrogen: P = 2000 kPa, 120 K, v = ?, Z = ?b. Nitrogen: 120 K, v = 0.0050 m3/kg, Z = ?c. Air: T =
Find the phase and the missing properties of P, T, v, u, and x for water ata. 500 kPa, 100◦Cb. 5000 kPa, u = 800 kJ/kgc. 5000 kPa, v = 0.06 m3/kgd. −6◦C, v = 1 m3/kg
Find the missing property of P, T, v, u, h, and x and indicate the states in a P–v and a T–v diagram fora. Water at 5000 kPa, u = 1000 kJ/kgb. R-134a at 20◦C, u = 300 kJ/kgc. Nitrogen at 250 K,
Determine the phase and the missing properties.a. H2O 20◦ C, v = 0.001000 m3/kg P = ?, u = ?b. R-410a 400 kPa, v = 0.075 m3/kg T = ?, u = ?c. NH3 10◦C, v = 0.1 m3/kg P = ?, u = ?d. N2 101.3 kPa,
Find the missing properties of u, h, and x fora. Water at 120◦C, v = 0.5 m3/kgb. Water at 100◦C, P = 10 MPac. Nitrogen at 100 K, x = 0.75d. Nitrogen at 200 K, P = 200 kPae. Ammonia at 100◦C, v
Determine the phase of the following substances and find the values of the unknown quantities.a. R-410a: T =−20◦C, u=220 kJ/kg, P=?, x=?b. Ammonia: T =−20◦C, v = 0.35 m3/kg, P = ?, u = ?c.
Find the missing properties for carbon dioxide ata. 20◦C, 2 MPa: v = ? and h = ?b. 10◦C, x = 0.5: T = ?, u = ?c. 1 MPa, v = 0.05 m3/kg: T = ?, h = ?
Find the missing property of P, T, v, u, h, and x and indicate the states in a P–v and a T–v diagram fora. R-410a at 500 kPa, h = 300 kJ/kgb. R-410a at 10◦C, u = 200 kJ/kgc. R-134a at 40◦C, h
Determine the phase of the following substances and find the values of the unknown quantities.a. Water: P=500 kPa, u=2850 kJ/kg, T =?, v=?b. R-134a: T = −10◦C, v = 0.08 m3/kg, P = ?, u = ?c.
Take the whole room as a C.V. and write both conservation of mass and conservation of energy equations. Write equations for the process (two are needed) and use them in the conservation equations.
Consider a steel bottle as a CV. It contains carbon dioxide at−20◦C, quality 20%. It has a safety valve that opens at 6 MPa. The bottle is now accidentally heated until the safety valve opens.
A piston/cylinder contains water with quality 75% at 200 kPa. Slow expansion is performed while there is heat transfer and the water is at constant pressure. The process stops when the volume has
The final state was given, but you were not told that the piston hits the stops, only that Vstop = 2 V1. Sketch the possible P–v diagram for the process and determine which number(s) you need to
Take Problem 3.210 and write the left-hand side (storage change) of the conservation equations for mass and energy. How should you write m1 and Eq. 3.5?Data from Problem 3.210A rigid tank is divided
Two rigid insulated tanks are connected with a pipe and valve. One tank has 0.5 kg air at 200 kPa, 300 K and the other has 0.75 kg air at 100 kPa, 400 K. The valve is opened and the air comes to a
Look at Problem 3.183 and plot the P–v diagram for the process. Only T2 is given; how do you determine the second property of the final state? What do you need to check, and does it influence the
A constant-pressure piston/cylinder assembly contains 0.2 kg of water as saturated vapor at 400 kPa. It is now cooled so that the water occupies half of the original volume. Find the work and heat
Saturated vapor R-410a at 0◦C in a rigid tank is cooled to −20◦C. Find the specific heat transfer.
Ammonia at 0◦C with a quality of 60% is contained in a rigid 200-L tank. The tank and ammonia are now heated to a final pressure of 1 MPa. Determine the heat transfer for the process.
A rigid tank contains 1.5 kg of R-134a at 40◦C, 500 kPa. The tank is placed in a refrigerator that brings it to −20◦C. Find the process heat transfer and show the process in a P–v diagram.
Two kilograms of water at 120◦C with a quality of 25% has its temperature raised 20◦C in a constant volume process as in Fig. P3.95. What are the heat transfer and work in the process? FIGURE
A piston/cylinder contains 1.5 kg of water at 200 kPa, 150◦C. It is now heated by a process in which pressure is linearly related to volume to a state of 600 kPa, 350◦C. Find the final volume,
A piston/cylinder device contains 50 kg water at 200 kPa with a volume of 0.1m3. Stops in the cylinder are placed to restrict the enclosed volume to a maximum of 0.5 m3. The water is now heated until
Ammonia (0.5 kg) in a piston/cylinder at 200 kPa, −10◦C is heated by a process in which pressure varies linearly with volume to a state of 120◦C, 300 kPa. Find the work and heat transfer for
A water-filled reactor with a volume of 1 m3 is at 20 MPa and 360◦C and is placed inside a containment room, as shown in Fig. P3.101. The room is well insulated and initially evacuated. Due to a
A rigid tank holds 0.75 kg ammonia at 70◦C as saturated vapor. The tank is now cooled to 20◦C by heat transfer to the ambient temperature. Which two properties determine the final state?
A piston/cylinder assembly contains 2 kg of liquid water at 20◦C and 300 kPa, as shown in Fig. P3.48. There is a linear spring mounted on the piston such that when the water is heated, the pressure
A400-L tank,A(see Fig. P3.47), contains argon gas at 250 kPa and 30◦C. Cylinder B, having a frictionless piston of such mass that a pressure of 150 kPa will float it, is initially empty. The valve
A 2-kg piston accelerates to 20 m/s from rest. What constant gas pressure is required if the area is 10 cm2, the travel is 10 cm, and the outside pressure is 100 kPa?
Two hydraulic piston/cylinders are connected with a line. The master cylinder has an area of 5 cm2, creating a pressure of 1000 kPa. The slave cylinder has an area of 3 cm2. If 25 J is the work input
A steel ball weighing 5 kg rolls horizontally at a rate of 10 m/s. If it rolls up an incline, how high up will it be when it comes to rest, assuming standard gravitation?
Solve Problem 3.34, but assume that the steam pressure in the cylinder starts at 1000 kPa, dropping linearly with volume to reach 100 kPa at the end of the process.Data from Problem 3.34,Airplane
You mix 20◦Cwater with 50◦Cwater in an open container. What do you need to know to determine the final temperature?You mix 20◦Cwater with 50◦Cwater in an open container. What do you need to
An ideal gas in a piston/cylinder is heated with 2 kJ during an isobaric process. Is the work positive, negative, or zero?
An ideal gas in a piston/cylinder is heated with 2 kJ during an isothermal process. How much work is involved?
A rigid tank with pressurized air is used (a) To increase the volume of a linear spring-loaded piston/ cylinder (cylindrical geometry) arrangement and (b) To blow up a spherical balloon.
Look at the R-410a value for uf at −50◦C. Can the energy really be negative? Explain.
Liquid water is heated, so it becomes superheated vapor. Can specific heat be used to find the heat transfer? Explain.
Liquid water is heated, so it becomes superheated vapor. Should u or h be used in the energy equation? Explain.
Verify that a surface tension s with units N/m also can be called a surface energy with units J/m2. The latter is useful for consideration of a liquid drop or liquid in small pores (capillary).
On a chilly 10◦C fall day a house, with an indoor temperature of 20◦C, loses 6 kW by heat transfer. What transfer happens on a warm summer day with an indoor temperature of 30◦C, assuming
A piece of steel has a conductivity of k = 15 W/mK and a brick has k =1W/mK. How thick a steel wall will provide the same insulation as a 10-cm-thick brick?
Figure P3.14 shows three physical situations; show the possible process in a P–v diagram. Po m, "p R-410a (a) (b) (c) FIGURE P3.14
Assume the physical situation in Fig. P3.11b; what is the work term a, b, c, or d?a. 1w2 = P1(v2 − v1)b. 1w2 = v1(P2 − P1)c. 1w2 = 1/2 (P1 + P2) (v2 − v1)d. 1w2 = 1/2 (P1 − P2) (v2 + v1)
For the indicated physical setup in (a), (b), and (c) in Fig. P3.11, write a process equation and the expression for work. R-410a (a) (b) (c)

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