ENGR 130 MIDTERM 1
An apple is chosen from an group of apples for which the group has an average mass of 0.18 kg and average specific heat of 3.65 kJ/kg·°C. The apple is cooled from 13°C to 5°C. The amount of heat transferred from the apple is _____ kJ.
5.3 (HOMEWORK 3)
Which of the following statements are true regarding the similarities between heat and work?
-Both heat and work are path functions. -Both heat and work are associated with a process. -Both heat and work can cross the boundary of a system.
Select the statements below that best express the first law of thermodynamics.
-Energy can neither be created nor destroyed. -The change in the total energy for a closed system during an adiabatic process must be equal to the net work input. -Energy is conserved.
Select all of the ways in which a process can be adiabatic.
-The system is well insulated. -The system is at the same temperature as the surroundings.
Heat is added to a system to raise its temperature 10oC in 20 minutes. If the rate of heat transfer were cut in half, how long would the process have to run in order to transfer an equivalent amount of heat?
40 minutes
The specific heat of liquid water is approximately 4.2 kJ/kg⋅K. If liquid water is heated up by 10°C, determine the change in internal energy.
42 kJ/kg (The change in internal energy is the specific heat times the change in temperature)
The Rankine scale of temperature equals the Fahrenheit scale plus ______.
459.67 T(R) = T(∘F) + 459.67
8 kW of shaft work is done on a system while 3 kW of heat is lost from the system. What is the rate of energy change of the system?
5 kW
True or false: Quality is defined as ratio of the volume of vapor to the total volume of the mixture.
False, it's vapor mass
True or False: Dimensional homogeneity means every term on each side of an equation must have the same unit.
True
True or False: Mathematically speaking, the boundary of a system has zero thickness.
True
True or False: Specific gravity is a dimensionless quantity.
True
True or False: Specification of two independent intensive properties in a simple compressible system is sufficient to define a state.
True
True or False: The molar specific volume of a system is defined as the ratio of the volume of the system to the number of moles of substance contained in the system, so the molar specific volume is an intensive property.
True
True or false: Following the formal sign convention, work done by a system (or work output) is defined as positive.
True
True or false: The boundary work for a constant volume process is always Zero.
True
True or false: The principle of corresponding states shows that the Z factor for all gases is approximately the same at the same reduced pressure and reduced temperature.
True
True or false: Two aluminum spheres with the same mass are located at different elevations. The sphere located at a higher elevation will possess greater potential energy.
True
Is iced water a pure substance?
Yes, iced water is a pure substance because it has the same chemical composition throughout.
A propane tank is filled with a mixture of liquid and vapor propane. Can the contents of this tank be considered a pure substance?
Yes, the contents of this tank can be considered a pure substance since the chemical composition throughout the tank remains the same.
If an energy transfer takes place due to a temperature difference, the energy crossing the boundary of the system is in the form of ______.
heat
An adiabatic process is one in which there is no ______.
heat transfer
A substance that has a constant specific volume or density is called an _________ substance.
incompressible
When mass enters a system, the energy in the system ______.
increases
The sum of all microscopic forms of energy is called ______ energy.
internal
The sum of all the microscopic forms of energy is called _____ energy.
internal
The symbol ____ is used for the ratio of specific heats cp/cv?
k
What is the unit for specific enthalpy?
kJ/kg
From the list below, select all of the following that represent units for a rate of heat transfer.
kW
The amount of energy absorbed or released during a phase change process is called the_____ heat
latent
The internal energy that is required to undergo a phase transition and is associated with the binding forces between the molecules of a substance is called _____ energy.
latent
Which of the following properties best characterizes the energy absorbed by water as it melts from a solid to a liquid?
latent heat of fusion
The term uniform flow implies flows with no change with a specific ______.
location
At a given pressure, a substance in the saturated vapor phase will be at a _______ temperature than a superheated vapor.
lower
For a given pressure, a compressed liquid has _____ temperature than a saturated liquid.
lower
The _____ forms of energy are those a system possess as a whole with respect to some outside reference frame, such as kinetic and potential energies.
macroscopic
the _____ forms of energy are those a system possess as a whole with respect to some outside reference frame, such as kinetic and potential energies.
macroscopic
A closed system does not allow _____ to cross its system's boundary.
mass -A closed system does not allow mass to cross its system's boundary, but energy is allowed.
Total energy of a system can be classified in two groups: _____ and _____.
microscopic macroscopic
Pressure is defined as a ________ force exerted by a fluid per unit area.
normal
Efficiency can be expressed in terms of the desired ____ divided by the required _____.
output input
An expansion or compression process of a gas, where pressure and volume are related by P(V)^n = C, is called a(n) ______ process.
polytropic
The energy that a system possesses as a result of its elevation in a gravitational field is called _____.
potential energy
The electrical power is defined by the product of the _____ difference and the _____.
potential, V, or voltage current, I, electric current, or current flow
The second law of thermodynamics asserts that energy has _____ as well as _____.
quantity quality
In a steady-flow process, the mass within the control volume _____.
remains the same
On a T-v diagram, the region under the dome area between the saturated liquid and saturated vapor lines is known as the _____ region.
saturated mixture
The temperature at which a substance changes phase at a given pressure is called its _______.
saturation temp
In the following scenario, a cup of hot coffee left on the table eventually cools, but a cup of cold coffee in the same room never gets hot by itself. This phenomenon can be explained by the ______.
second law of thermodynamics
The ______ heat is the energy required to raise the temperature of a unit mass of a substance by one unit of temperature change.
specific
Density is defined as mass per unit volume. The reciprocal of density is called
specific volume
Systems A and B contain the same substance. If system A is a saturated vapor, and has the same pressure as system B, but system B has a higher enthalpy value than A, what phase is system B in?
superheated vapor
The mass or region outside the system is called the _____
surroundings
A _____ can be simply described as a region in space chosen for study.
system
An isothermal process is a process during which ______ remains constant.
temperature
Heat is a form of energy transfer by virtue of a _____ difference.
temperature
Two bodies that have reached thermal equilibrium will have the same ______.
temperature
The density of a substance is most likely dependent on _____. (Check all that apply.)
temperature pressure
Any equation that relates the _____, ________, and specific volume of a substance is called an equation of the state.
temperature and pressure
Two bodies are brought into contact in an isolated enclosure until they both reach the same temperature. The two bodies have reached a state of ______.
thermal equilibrium
The power transmitted by a shaft is proportional to the ____ and the ____speed.
torque rotational, angular, rotation, rotating, revolution, or shaft
The point at which solid, liquid, and vapor coexist in equilibrium on the P-T diagram is called the _______ point.
triple
True or false: For a pure substance, if its liquid and vapor can coexist in equilibrium, the liquid-vapor mixture at these states is called saturated liquid-vapor mixture.
true
true or false: Work is a form of energy interaction, and thus it is allowed to cross the boundary of a control volume.
true
The state postulate states that the state of a simple compressible system is completely specified by _____ independent _____ properties.
two, intensive
Extensive properties per ________ are called specific properties.
unit mass
Which one of the following multiphase systems would be classified as a pure substance?
A tank containing liquid nitrogen and nitrogen gas
Select all of the following statements that are true regarding the critical point.
At pressures above the critical pressure, there is no distinct phase change process. The saturated vapor state is identical to the saturated liquid state.
energy transfer is involved in each of the following systems.
- a rotating shaft -a rising piston -a gas turbine
Determine the boundary work done by a gas during an expansion process by plotting the given data on a P-V diagram on a graph paper and evaluating the area under the process curve if the pressure and volume values at various states are measured to be 300 kPa, 1 L; 290 kPa, 1.1 L; 270 kPa, 1.2 L; 250 kPa, 1.4 L; 220 kPa, 1.7 L; and 200 kPa, 2 L. (Please upload your response/solution using the controls provided below.)
(homework 3 question 5)
Complete each line of the following table on the basis of the conservation of energy principle for a closed system.
(homework 3 question 6)
Steam expands in a piston-cylinder device from 2 m^3 to 3 m^3 at a constant pressure of 500 kPa. Determine the boundary work for this process.
+500 [500*(3-2)]
Oxygen is maintained at 4 MPa and 20°C. The gas constant, the molar mass, the critical pressure, and the critical temperature of oxygen are R = 0.2598 kPa·m3/kg·K, M = 31.999 kg/mol, Tcr = 154.8 K, and Pcr = 5.08 MPa. Determine the specific volume of the oxygen under this condition as predicted by the ideal-gas equation of state. Determine the specific volume of the oxygen under this condition as predicted by the Beattie-Bridgeman equation of state Determine the specific volume of the oxygen under this condition as predicted by the compressibility factor.
0.01903 m^3/kg 0.01853 m^3/kg 0.01855 m^3/kg (homework 2)
For a cooking appliance, the overall energy supplied to the appliance is 5 kWh and only 4 kWh is transferred to the food. What is the appliance's efficiency?
0.8 Reason: Efficiency is defined by energy utilized divided by energy supplied to the appliance.
1 m3 of saturated liquid water at 200°C is expanded isothermally in a closed system until its quality is 80%. Determine the total work produced by this expansion, in kJ.
1.355 x 10^5 (homework 3)
A power plant produced 36000 kJ of work in an hour. How much power did it produce?
10 kW Reason: Power = Work/time = 36000/(60 × 60) = 10 kW
A 6-pack of canned drinks is to be cooled from 15°C to 3°C. The mass of each canned drink is 0.355 kg. The drinks can be treated as water, and the energy stored in the aluminum can itself is negligible. The amount of heat transfer from the six canned drinks is _____ kJ.
106.8 (HOMEWORK 3)
A system containing an electric device is well-insulated. If the energy of the system increases 16 kJ during a process, what is the electric work performed on the system?
16 kJ Reason: The change in the total energy during an adiabatic process must be equal to the net work done.
An ordinary egg with a mass of 0.6 kg and a specific heat of 3.32 kJ/kg·°C is dropped into boiling water at 95°C. If the initial temperature of the egg is 5°C, the maximum amount of heat transfer to the egg is _____ kJ.
179.3 (HOMEWORK 3)
A potato is baked in an oven. Considering that any moisture loss from the potato is disregarded and the oven is well insulated, if 2 kJ of heat is transferred to the potato, what is the energy change of the potato?
2 kJ Reason: The first law of thermodynamics must be preserved as energy can neither be created nor destroyed. If the potato receives a heat transfer of 2 kJ, then its energy must increase by 2 kJ as well.
A 1.86-m3 rigid tank contains steam at 220°C. One-third of the volume is in the liquid phase and the rest is in the vapor form. The properties of steam at 220°C are given as follows: vf = 0.001190 m3/kg and vg = 0.08609 m3/kg. Determine the pressure of the steam. (You must provide an answer before moving to the next part) Determine the quality of the saturated mixture. (You must provide an answer before moving to the next part) Determine the density of the mixture.
2320 kPa 0.0269 287.8 kg/m^3 (homework 2 question 1-3)
A room is filled with saturated steam at 100°C. Now a 5-kg bowling ball at 25°C is brought to the room. Heat is transferred to the ball from the steam, and the temperature of the ball rises to 100°C while some steam condenses on the ball as it loses heat (but it still remains at 100°C). The specific heat of the ball can be taken to be 1.8 kJ/kg·°C. The mass of steam that condensed during this process is _____ g.
299 (HOMEWORK 3)
10 kJ heat is transferred to a control volume and 7 kJ work is done by the control volume. The amount of heat lost from the control volume is
3 kJ out
Water is boiled at 2000-m elevation where the standard atmospheric pressure is 79.5 kPa. It is boiled in a 25-cm internal diameter stainless steel pan on an electric range. If it is observed that the water level in the pan drops by 9.2 cm in 45 min, determine the rate of heat transfer to the pan. The properties of water at 79.5 kPa are Tsat = 93.3°C, hfg = 2273.9 kJ/kg, and vf = 0.001038 m3/kg (Table A-5).
3.6641 kW (homework 2)
A process requires heat addition at a constant rate of 100 kW for 60 seconds. In order to add an equivalent amount of heat in 20 seconds, what rate of heat transfer would be required?
300 kW
Calculate the total work, in kJ, for process 1-3 shown in the figure when the system consists of 2.5 kg of nitrogen.
375 kJ (homework 3)
Refrigerant-134a at 400 psia has a specific volume of 0.13853 ft3/lbm. The gas constant, the critical pressure, and the critical temperature of R-134a are R = 0.1052 psia·ft3/lbm·R, Tcr= 673.6 R, and Pcr= 588.7 psia. Use data from the steam tables Determine the temperature of the refrigerant based on the ideal-gas equation. Determine the temperature of the refrigerant based on the van der Waals equation. Determine the temperature of the refrigerant based on the refrigerant tables.
526 R 689.6589 R 700 R (homework 2)
The torque applied to the shaft of a car is 180 N·m and the shaft rotates at a rate of 3000 rpm. What is the power transmitted through the shaft?
56.52 kW Wsh. = 2πn∙T Wsh. = 2π×3000/60×180/1000Wsh. = 56.52 kW
A well-sealed room contains 60 kg of air at 200 kPa and 20°C. Now solar energy enters the room at an average rate of 0.8 kJ/s while a 120-W fan is turned on to circulate the air in the room. If heat transfer through the walls is negligible, the air temperature in the room in 30 min will be ____°C.
58.44 (HOMEWORK 3)
What is the specific volume of oxygen at 25.5 psia and 80°F? The gas constant of oxygen is R = 0.3353 psia·ft3/lbm·R.
7.0961 ft^3/lbm. (homework 2)
A room contains 75 kg of air at 100 kPa and 15°C. The room has a 250-W refrigerator (the refrigerator consumes 250 W of electricity when running), a 120-W TV, a 1.8-kW electric resistance heater, and a 50-W fan. During a cold winter day, it is observed that the refrigerator, the TV, the fan, and the electric resistance heater are running continuously but the air temperature in the room remains constant. The rate of heat loss from the room that day is _____ kJ/h.
7992 (HOMEWORK 3)
A 400-L rigid tank contains 5 kg of air at 25°C. Determine the reading on the pressure gage if the atmospheric pressure is 97.5 kPa. The gas constant of air is R = 0.287 kPa·m3/kg·K.
971.6 kPa (homework 2)
Which of the following is not true regarding heat transfer?
A system at a high temperature possesses more heat than a system at a lower temperature.
From the list below, select all of the processes where boundary work occurs.
Air is compressed by a piston inside of a cylinder. A balloon is filled with helium.
Work is the energy transfer associated with _____ acting through a distance
Blank 1: force, a force, or forces
In the absence of magnetic, electric, and surface tension effects, the total energy of a system consists of the _____ ,_____ , ______ and energies.
Blank 1: potential Blank 2: kinetic Blank 3: internal
Power is defined by _____ per unit _____.
Blank 1: work, work done, or the work Blank 2: time
Energy can exist in many forms. Which of the following is an energy form?
Chemical Potential Kinetic Electrical
______ is the transfer of energy between a solid surface and the adjacent fluid that is in motion.
Convection
True or false: Heat and work are point functions.
False
True or false: Heat transfer from a system is positive.
False
True or false: All isothermal processes are adiabatic. True false question.
False Reason: In an isothermal process, a body may accept or reject heat, but not change its temperature. For example, a fluid undergoing a phase change may be heated or cooled, changing its phase, but not its temperature.
Knowing the compressibility factor of the following gases, which gas's behavior below deviates the most from ideal gas behavior?
Gas E, Z=0.2 Reason: The further Z is away from unity, the more the gas deviates from ideal gas behavior.
Heat transfer----> kJ Heat transfer per unit mass---> kJ/kg Rate of heat transfer --->kW
HI
Select all of the statements below that use heat in the thermodynamic sense.
Heat is transferred from a warmer body to a cooler one. A fire is used to heat a pot of water.
Which of the following statements describes the saturated vapor?
It is still a 100% vapor. It is about to condense. It refers to a point on a T-v diagram at a specific temperature. Any heat removed will cause some of the vapor to condense.
Which energy form(s) of the following is macroscopic?
Kinetic energy Electrical energy Potential energy
Which of following energy is not microscopic?
Mechanical energy
A person has to satisfy his hunger without consuming too many calories by consuming either generous amounts of bread and rice or generous amounts of margarine and butter. Is consuming margarine and butter a better option to satisfy his hunger without consuming too many calories?
NO. 1 kg of natural fat contains almost 8 times the metabolizable energy of 1 kg of natural carbohydrates. Therefore, a person who fills his stomach with carbohydrates will satisfy his hunger without consuming too many calories.
Is the metabolizable energy content of a food the same as the energy released when it is burned in a bomb calorimeter?
No, the food we eat is not entirely metabolized in the human body. The fraction of metabolizable energy contents are 95.5% for carbohydrates, 77.5% for proteins, and 97.7% for fats. Therefore, the metabolizable energy content of a food is not the same as the energy released when it is burned in a bomb calorimeter.
Which following energy forms of a system are microscopic?
Nuclear energy Sensible energy Latent energy
On a P-v diagram, what does the area under the process curve represent?
Quasi-equilibrium process
Which of the following represents the rate form of the first law?
Q∙ − W∙ = dE/dt (rate forms of heat and work get dots)
Select all of the mechanisms of heat transfer from the list below.
Radiation Convection Conduction
Which ones of the following are examples of mechanical work?
Shaft work Spring work
The processes A, B, and C represent three potential paths between states 1 and 2. Which path requires the least amount of work?
The boundary work is PdV or the area under each curve. Process A requires the least amount of work.
An ideal gas (cv = 2 kJ/kg-K, cp = 3 kJ/kg-K) is heated from 100 to 200°C. Determine the change in enthalpy.
The change in enthalpy of an ideal gas is given by the following relation: Δh = cp(T2-T1) = 300 kJ.
An incompressible substance with a density of 1000 kg/m3 is isothermally compressed from 100 to 1000 kPa. Determine the change in enthalpy.
The change in enthalpy of an incompressible substance during an isothermal process is equal to the specific volume multiplied by the change in pressure. In this case, that is (0.001 m3/kg)(1000 - 100 kPa) = 0.9 kJ.
An ideal gas (cv = 2 kJ/kg.K, cp = 3 kJ/kg.K) is heated from 100 to 200°C. Determine the change in internal energy.
The change in internal energy of an ideal gas is given by the following relation. Δu = cv(T2-T1) = 200 kJ.
A 5 kg piece of metal (c = 0.5 kJ/kg-K) is heated from 50 to 150°C. Determine the change in internal energy.
The change in internal energy of an incompressible substance is m c ΔT. In this case, that is 250 kJ.
An ideal gas (cv = 2 kJ/kg-K, cp = 3 kJ/kg-K) is heated from 100°C to 200°C. Determine the gas constant for the gas.
The following relationship can be used to determine the gas constant. R = cp - cv = 1 kJ/kg-K.
In the absence of compressed liquid tables, the compressed liquid can be approximated as a saturated liquid at a given temperature
This is true. In the absence of compressed liquid tables, the compressed liquid can be approximated as a saturated liquid at a given temperature.
Which of the following best defines the term boundary work?
Work associated with expansion or compression of a moving boundary
Does the amount of heat absorbed as 1 kg of saturated liquid water boils at 100°C have to be equal to the amount of heat released as 1 kg of saturated water vapor condenses at 100°C?
Yes. Otherwise we can create energy by alternately vaporizing and condensing a substance.
At supercritical pressures, there is no distinct phase change process, whereas, at subcritical pressures, there is always a distinct surface between the phases.
[True] At supercritical pressures, there is no distinct phase change process, whereas, at subcritical pressures, there is always a distinct surface between the phases.
Two gases—neon and air—are compressed in a closed system from P1 to P2 using a polytropic process with n = 1.5. _____ requires lesser work to be compressed. The gas constants for neon and air are R = 0.4119 and 0.287 kJ/kg·K, respectively.
air
Select all of the following statements that are true. Multiple select question. At a given pressure in the superheated region, the specific volume decreases as temperature increases. At a given pressure, the temperature of a saturated vapor is usually greater than that of a saturated liquid. At higher pressures, the difference in specific volume between saturated liquids and saturated vapors of the same pressure decreases. As pressure increases, the saturation temperature of a substance increases.
at higher pressures..., as pressure increases...
Water in a tank is at the pressure of 5.5 MPa and temperature of 260oC. The saturation pressure at the same temperature is 4.69 MPa. What is the phase of water?
compressed liquid
On a P-T diagram, the vaporization line ends at the ________ point because no distinction can be made between liquid and vapor phases above it.
critical
The reduced pressure and reduced temperature PR and TR are temperature and pressure normalized with respect to their _____ counterparts.
critical
The electrical power equals to the square of the _____ multiplying the resistance.
current, I
h_f = h_g = h_fg =
enthalpy of saturated liquid enthalpy of saturated vapor/gas enthalpy of vaporization
Which of the following statements are true?
- Properties are considered to be either intensive or extensive. - Extensive properties per unit mass are called specific properties.
Which of the following systems are applications of thermodynamics?
-A car engine -A refrigerator -A solar hot water system
Select the correct statements regarding the definition of cycle.
-A cycle has identical initial and final states. -A cycle always returns to its initial state at the end of the process. -A cycle may include multiple processes.
For the following devices in normal operation, which ones can be approximated as steady-flow devices?
-A heat exchanger -A turbine -A centrifugal pump
Which of the following systems/devices demonstrates application of thermodynamic principles?
-A humidifier -A pressure cooker -A car radiator -A water heater
Which of the following statement(s) is(are) true?
-At a given state, all the properties of a system have fixed values. -In an equilibrium state, there are no unbalanced potentials. -If the value of one property changes value within the system, the state will change.
Which of the following statement(s) is(are) true? -If the value of one property changes value within the system, the state will change. -At a given state, all the properties of a system have fixed values. -For a system in a given state, if one property changes value, the state will remain unchanged. -At a given state, only the intensive properties of a system have fixed values. -In an equilibrium state, there are no unbalanced potentials.
-If the value of one property changes value within the system, the state will change. -At a given state, all the properties of a system have fixed values. -In an equilibrium state, there are no unbalanced potentials.
Which of the following is true for pressure? (Select all that apply.)
-Pressure is defined as a normal force exerted by a fluid per unit area. -Pressure in fluid systems is similar to normal stress for a solid.
A system is a simple compressible system in the absence of _____ and surface tension effects. (Select all that apply.)
-electrical -motion -gravitational -magnetic
A tank contains 5 kg of a saturated liquid-vapor mixture with 3 kg in the liquid phase. Determine the quality of the mixture.
0.4 [(5-3)/5]
Given the density of water at 1000 kg/m3. If the density of a substance is 790 kg/m3, what is its specific gravity?
0.79
If the gas pressure inside a sealed tank is 689 kPa absolute, what is this pressure in pounds force per square inch?
100 psia Reason: 6.89 kPa = 1 psi
How many bytes of data are in one Terabyte?
10^12
How many meters are in one kilometer?
10^3
1 atm can be approximated to be 14.7 psi. If a tire's gage pressure is 100 psi, what is its corresponding absolute pressure?
114.7 psi Reason: Pabs = Pgage + Patm
300 K is equal to ______ ∘C.
26.85 T(∘C) = T(K) - 273.15
The Kelvin scale of temperature equals the Celsius scale plus ____.
273.15 T(K) = T(∘C) + 273.16
An object whose mass is 145 kg is located 20 m above a datum level in a location where standard gravitational acceleration exists. Determine the total potential energy, in kJ, of this object.
28.449 kJ PE=mgz PE=(145 kg)(9.81 m/s^2)(20 m)(1 kJ/kg1000 m^2/s^2)
The density of water is assumed to be a constant of 1000 kg/m3. If the gage pressure of a water column 10 m high is 10 kPa, then the gage pressure of a water column 30 m high should be _____.
30 kPa
The absolute pressure in a compressed air tank is 250 kPa. What is this pressure in psia?
36.26 psia P=(250 kPa)(1 psia/6.895 kPa)
Convert 98oF to oC.
37 T(∘F) = 1.8 T(∘C) + 32
A vacuum gage connected to a chamber reads 45 kPa at a location where the atmospheric pressure is 92 kPa. Determine the absolute pressure in the chamber.
47 kPa Pabs=Patm−Pvac=92 kPa−45 kPa=47 kPa
How much kilojoule is 5 Btu of energy using the unit conversion ratio to make the calculation?
5.275 kJ (5 Btu)(1.055056 kJ/1 Btu)
Determine the specific kinetic energy of a mass whose velocity is 110 m/s, in kJ/kg.
6.05 kJ/kg emech=ke=V^2/2 ke=((110 m/s)^2/2)(1 kJ/kg1000 m2/s2)
At a certain location, wind is blowing steadily at 10 m/s. Determine the mechanical energy of air per unit mass and the power generation potential of a wind turbine with 80-m-diameter (D) blades at that location. Take the air density to be 1.25 kg/m3.
62831.8531 kg/s 3141.5927 kW
Ten horsepower (hp) is how many kilowatts (kW) of power using the unit conversion ratio to make the conversion?
7.457 kW
Ten horsepower (hp) is how many kilowatts (kW) of power using the unit conversion ratio to make the conversion?
7.457 kW (10 hp)(0.7457kW/1hp)
Consider the following example. A liquid is heated at constant pressure until it exists as a gas. At which of the following states would it be considered a saturated vapor?
All of the mass is in vapor phase, and the substance is at its boiling point. If any heat were lost, the substance would start to condense.
Consider the following example. A liquid is heated at constant pressure until it exists as a gas. At which of the following states would it be considered a saturated liquid?
All of the mass is liquid and the temperature has reached the boiling point. If any more heat is added, the substance will start to vaporize.
If a system reaches a given state, which of following statements is true?
All the properties of the system have fixed values.
Which of following devices is not suitable for using a control volume (open system) in the thermodynamic analysis of the system?
Compressed nitrogen in a sealed tank
Which of the following dimension(s) is a primary dimension of the English system? -Length (ft) -Temperature (R) -Mass (lbm) -Power (hp) -Energy (Btu)
Length (ft) Temperature (R) Mass (lbm)
If a substance is assumed incompressible, which of its properties can be considered as constant?
Density
For an ideal gas under a constant pressure, if the volume is doubled, the temperature of the gas will ______.
Double
True or False: A rigid tank containing ionized gases kept under the influence of a magnetic field is a simple compressible system.
False
True or False: Any characteristic of a system is called a thermodynamic state.
False
True or False: The weight of a system is an intensive property.
False
True or false: Compared with solids, the distances between molecules increase for all solids when they turn into liquids.
False
True or false: Water at 100oC is always a saturated liquid.
False
Which of following statement does not describe the saturated liquid if heat is added to it? It is about to vaporize. It's still considered a liquid. Any heat added will cause some of the liquid to vaporize. It's about to condense. It refers to a point on a T-v diagram.
It is about to condense
Besides length and time, which of the following is a primary dimension of the SI metric system?
Mass (kg)
From the following properties, select the properties that are not classified as an intensive property. (Check all that apply.)
Momentum Total mass
From the following properties, select one that is not classified as an extensive property.
Pressure
An office worker claims that a cup of cold coffee on his table can warm up to 80°C itself by picking up energy from the surrounding air, which is at 25°C, as long as the air has sufficient energy. Which thermodynamic law does his claim violate?
Second law of thermodynamics
Which one of the following is a quasi-equilibrium process?
Slow and steady compression of air in a cylinder
Which property remains constant if the process is isochoric?
Specific volume
From the following properties, select all that are classified as intensive. (Check all that apply.)
Temperature Pressure
Which of the following are equations of state?
The Beattie-Bridgeman equation The ideal gas law The van der Waals equation The Benedict-Webb-Rubin equation
A rigid tank contains an ideal gas. If the temperature is doubled, the pressure of the gas will ______.
double
Select the primary dimensions of the SI systems.
Time (s) Mass (kg) Temperature (K) Length (m)
Which of the following best defines a liquid?
The molecular spacing is similar to that of a solid, but the molecules are not fixed with respect to each other.
Which of the following statements are true regarding gas?
The molecules are far apart from each other, and a molecular order is nonexistent. Molecules move about at random in the gas phase. It must release a large amount of energy before it can condense.
True or false: The first law of thermodynamics states firmly that energy is a thermodynamic property.
True
True or False: Absolute pressure is always higher than gage pressure when the environment is not in vacuum.
True Reason: Pabs = Patm + Pgage,since Patm is always positive.
Consider the following example. A liquid is heated at constant pressure until it exists as a gas. At which of the following states would it be considered a saturated liquid-vapor mixture?
The substance is at the boiling point and both liquid and vapor phases are present.
From the following list, select those that characterize a system, also known as the system's properties.
Thermal conductivity Pressure Viscosity
The gage pressure in a liquid of constant density ______ when the liquid depth is doubled.
doubles
Which of the following properties are extensive?
Volume Weight Mass
Which of the following topics is beyond the scope of thermodynamics?
Young's modulus of an alloy
Any characteristic of a system is called _____.
a property
A____is a real or an imaginary surface separating the system and the surroundings.
boundary, control surface, or system boundary
The idea that energy cannot be _____ or _____ , but can change from one form to another is an expression of the first law of thermodynamics.
created destroyed
The point at which saturated liquid is identical to saturated vapor is called the _______ point.
critical
A system is said to have undergone a _____ if it returns to its initial state at the end of the process.
cycle
The second law of thermodynamics implies that heat flows automatically in the direction of _____.
decreasing temperature
If the gas in a piston-cylinder device undergoes a quasi-equilibrium compression, the pressure in a system ______.
is approximately uniform throughout the system at each moment in time
On a T-v diagram, in the region under the dome between the saturated liquid and saturated vapor lines, the substance exists as a ______.
mixture of liquid and vapor
The series of states through which a system passes during a process is called the ____ of the process. (Use one word to fill the blank.)
path
An isobaric process is a process during which ____ remains constant.
pressure
Any change that a system undergoes from one equilibrium state to another is called a ______.
process
Which of the following units are units of pressure?
psi mmHg Pa
System A is a thermometer. Systems A, B, and C are not in contact with one another but all have the same temperature. It can be stated that systems B and C are in thermal equilibrium because of the ______ law of thermodynamics.
zeroth
System A is in thermal equilibrium with system B. System C is also in thermal equilibrium with system B. We can derive that systems A, B, and C are all in thermal equilibrium based on the ______ law of thermodynamics.
zeroth