In the winter season, you are using the same system as stated in (c) but as a Carnot heat pump. The system adds heat at a rate of 1000 kJ/min to maintain similar temperature inside of the house with an average outdoor temperature of −10 ∘ C.
i) Sketch a schematic diagram of the heat pump system.
ii) Calculate the coefficient of performance (COP) of the system.
iii) Determine the net power input to operate this system, kW.
iv) After using the system for the whole winter season, the measured net power input to the system had changed to 2 kW. State one (1) possible reason on the change of the net power input of the system after it has been used for long period of time.
Answers
i) Schematic diagram of the Carnot heat pump system:
Outside (−10 °C) --> Compressor --> Condenser (1000 kJ/min) --> Expansion Valve --> Evaporator --> Inside
ii) To calculate the coefficient of performance (COP) of the system, we can use the formula:
COP = Q_h / W_net
Q_h: Heat absorbed from the outside (Condenser)
W_net: Net work input to the system
Since it's a Carnot heat pump, the heat absorbed from the outside is equal to the heat rejected to the inside.
Therefore, Q_h = 1000 kJ/min.
The net work input to the system can be calculated using the formula:
W_net = Q_h / COP
Since it's a Carnot heat pump, the COP is given by:
COP = T_h / (T_h - T_c)
T_h: Temperature of the heat source (Condenser) = −10 °C + 273.15 = 263.15 K
T_c: Temperature of the heat sink (Evaporator) = Average indoor temperature
Calculate the COP using the given values and substitute it into the net work input equation to find the COP of the system.
iii) To determine the net power input to operate the system, we need to convert the heat transfer rate of 1000 kJ/min to kW.
1 kW = 60 kJ/min
Divide the heat transfer rate by 60 to obtain the net power input in kW.
iv) One possible reason for the change in the net power input of the system after it has been used for a long period of time could be the degradation or inefficiency of components such as the compressor or heat exchangers. Over time, wear and tear, as well as accumulation of deposits, can reduce the efficiency of the system, leading to increased power consumption. Regular maintenance and cleaning of the system can help mitigate this issue.
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Related Questions
Tech a says that a brake-by-wire system can start to apply brakes before the driver can step on the brake pedal. tech b says that brake-by-wire systems use heavy cables to transmit the brake pedal force to the wheel brake units. who is correct?
Answers
A brake-by-wire technology, according to Tech A, applies individual braking units to each wheel.
There are three different types of brake-by-wire technologies being used in the automotive industry to advance braking systems: electro-hydraulic, entirely electric, and a hybrid of the two. A brake booster is not required thanks to the electro-hydraulic system. Although there aren't any entirely drive-by-wire production cars yet, several car makers have created concept cars that satisfy the bill. To put it another way, a drive-by-wire system uses an electrical signal to instruct the engine on how much power to produce. The latter (drive-by-cable) still transmits data from the accelerator pedal to the engine through a mechanical cable.
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Where you attend college could costmore to borrow and refinance loans
Answers
which of the following is a function of a safety device
Answers
Answer:
what are the options available?
A bona fide established commercial marketing agency is a business which is specifically devoted to public relations, advertising and promoting the services of a client. True or False
Answers
Answer:
True
Explanation:
Bona Fide is a Latin term which means in good faith or without any intention to deceive. The business established on a bona fide basis means that there is an absence of fraud. The marketing agency has devoted its services to public relations, advertising and promoting the services of clients. There is no intention of fraud in the business.
Under a subsection for geological hazards the buyer is encouraged to obtain an read the booklet
Answers
Answer:
Buyer is encouraged to obtain and read the booklet entitled "The Homeowners Guide to Earthquake Safety." In most cases a questionnaire within the booklet must be completed by Seller and the entire booklet given to the Buyer if the Property was built prior to 1960.
There are two potential fall hazards in this image. What are they?
Answers
Answer:
Lack of fall protection and Scaffold is overloaded
; How do engineers make a difference in the world and with proof ?
Answers
if the height of a 12 in. wide rectangular beam section is increased from 16 in. to 32 in. (i.e., initial section is 12x16 in. and final section is 12x32 in.), the maximum flexure or bending stress in the beam becomes?
Answers
The maximum flexure or bending stress in the beam is increased by a factor of 4.
The maximum flexure or bending stress in a beam is calculated using the equation:
σ = Mc/I
Where,
σ = Maximum flexure or bending stress (MPa)
M = Maximum bending moment (N.m)
c = Distance from Neutral Axis to outermost fibre (mm)
I = Moment of Inertia (mm4)
For the given beam,
Initial Section: 12 x 16 in.
Final Section: 12 x 32 in.
For the initial section:
I1 = b1 x h12^3/12 = 12 x 162^3/12 = 24576 in4
For the final section:
I2 = b2 x h22^3/12 = 12 x 322^3/12 = 98304 in4
Therefore, the Moment of Inertia (I) is increased by a factor of 4 (I2 = 4 x I1).
Since M and c remain unchanged, the maximum flexure or bending stress (σ) is increased by a factor of 4 (σ2 = 4 x σ1).
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Generic Motors (GM) is making plans for its weekly operation for next year. GM makes three lines of
cars: Luxury (L), Mid-sized (M), and Economy (E). They have divided the country into four regions:
Northeast (NE), Northwest (NW), Southeast (SE) and Southwest (SW). They have two factories that can
ship to the four distribution center via train. Each distribution center will need to provide cars to the
dealers in that region; this is done via trucking. Note that since customers need their cars within a week,
everything is built on a weekly production and shipment schedule. The following information is included:
1) Production costs and capacities at the two factories for the three lines.
2) Retail cost of the three lines.
I
3) A weekly demand model for each of the four regions.
4) Shipping information from the factories to the distribution center of the four regions.
5) Shipping information from the distribution center to the dealers.
You have been asked to maximize the expected weekly profit for GM.
Make sure the spreadsheet is well documented! Use the color coding and headers we used all
semester long. You do not need to reproduce the spreadsheet in the report except the decision tree,
and a summary of your results.
Answers
A designer wishes to create a BJT amplifier with a gm of 30mA/V and a base input resistance of 3000 ohm or more. what collector-bias current should he choose? what is the minimum beta he can tolerate for the transistor used?
Answers
The minimum beta is given as 90 for which the tolerance of the transistor can be used.
How to solve for the minimum betaWe have the following values to solve this question with
gm of amplifier = 30mA/V
input resistance = 3000 ohm
We have transconductance as
\(\frac{I_{c} }{V_{T} } = 30mA/V\)
We have to consider the thermal voltage at Vt = 25mV when i tis occuring at the room temperature.
The collector bias would be solved by
Ic = 0.03Vt
= 0.03 x 0.025
= 0.75mA
Then we have to solve for the minimum value of the dc current as
β = gmγm
= 0.03 * 3000
= 90
Hence the minimum beta is given as 90
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Determine the design moment strength for a W21x73 steel beam with a simple span of 18 ft when lateral bracing for the compression flange is provided at the ends only (i.e., Lb
Answers
This question is incomplete, the complete question is;
Determine the design moment strength (ϕMn) for a W21x73 steel beam with a simple span of 18 ft when lateral bracing for the compression flange is provided at the ends only (i.e., Lb = 18 ft). Report the result in kip-ft.
Use Fy=50 ksi and assume Cb=1.0 (if needed).
Answer: the design moment strength for the W21x73 steel beam is 566.25 f-ft
Explanation:
Given that;
section W 21 x 73 steel beam;
now from the steel table table for this section;
Zx = Sx = 151 in³
also given that; fy = 50 ksi and Cb = 1.0
QMn = 0.9 × Fy × Zx
so we substitute
QMn = 0.9 × 50 × 151
QMn = 6795 k-inch
we know that;
12inch equals 1 foot
so
QMn = 6795 k-inch / 12
QMn = 566.25 f-ft
Therefore the design moment strength for the W21x73 steel beam is 566.25 f-ft
(35-39) A student travels on a school bus in the middle of winter from home to school. The school bus temperature is 68.0° F. The student's skin temperature is 94.4° F. Determine the net energy transfer from the student's body during the 20.00 min ride to school due to electromagnetic radiation. Note: Skin emissivity is 0.90, and the surface area of the student is 1.50m2.
Answers
Answer:
The net energy transfer from the student's body during the 20-min ride to school is 139.164 BTU.
Explanation:
From Heat Transfer we determine that heat transfer rate due to electromagnetic radiation (\(\dot Q\)), measured in BTU per hour, is represented by this formula:
\(\dot Q = \epsilon\cdot A\cdot \sigma \cdot (T_{s}^{4}-T_{b}^{4})\) (1)
Where:
\(\epsilon\) - Emissivity, dimensionless.
\(A\) - Surface area of the student, measured in square feet.
\(\sigma\) - Stefan-Boltzmann constant, measured in BTU per hour-square feet-quartic Rankine.
\(T_{s}\) - Temperature of the student, measured in Rankine.
\(T_{b}\) - Temperature of the bus, measured in Rankine.
If we know that \(\epsilon = 0.90\), \(A = 16.188\,ft^{2}\), \(\sigma = 1.714\times 10^{-9}\,\frac{BTU}{h\cdot ft^{2}\cdot R^{4}}\), \(T_{s} = 554.07\,R\) and \(T_{b} = 527.67\,R\), then the heat transfer rate due to electromagnetic radiation is:
\(\dot Q = (0.90)\cdot (16.188\,ft^{2})\cdot \left(1.714\times 10^{-9}\,\frac{BTU}{h\cdot ft^{2}\cdot R^{4}} \right)\cdot [(554.07\,R)^{4}-(527.67\,R)^{4}]\)
\(\dot Q = 417.492\,\frac{BTU}{h}\)
Under the consideration of steady heat transfer we find that the net energy transfer from the student's body during the 20 min-ride to school is:
\(Q = \dot Q \cdot \Delta t\) (2)
Where \(\Delta t\) is the heat transfer time, measured in hours.
If we know that \(\dot Q = 417.492\,\frac{BTU}{h}\) and \(\Delta t = \frac{1}{3}\,h\), then the net energy transfer is:
\(Q = \left(417.492\,\frac{BTU}{h} \right)\cdot \left(\frac{1}{3}\,h \right)\)
\(Q = 139.164\,BTU\)
The net energy transfer from the student's body during the 20-min ride to school is 139.164 BTU.
The repair and rehabilitation of damaged or spalled concrete is done by removing the:____________A. Loose concreteB. CollapsingC. BreakageD. Bonding
Answers
Answer:
A. Loose concrete
Explanation:
Concrete is a solid composite structural material.It is the most used component in setting up a structure. Concrete is known for its very good ability to bear load, but can sometimes fail, or can be damaged. To rehabilitate or repair a concrete, the loose concrete must first be removed, so that the surface can be cleaned and well set before the material used for repair is applied on it.
Social Engineering as Art and Science The logic behind social engineering is simple - it can be easy to get all the information and access that one needs from any person as long as you know how to trick a person into giving you the data you need with the least resistance possible. By being able to pull off a social engineering trick, you will be able to get your hands on to a device, account, or application that you need to access in order to perform bigger hacks or hijack an identity altogether. That means that if you are capable of pulling of a social engineering tactic before attempting to go through all other hijacking tactics up your sleeve, you do not need to make additional effort to penetrate a system. To put this entire concept into simpler terms, social engineering is a form of hacking that deals with manipulation of victims through social interaction, instead of having to break right away into a computer system. What makes social engineering difficult is that it is largely based on being able to secure trust, which is only possible by getting someone's trust. For this reason, the most successful hackers are capable of reading possible responses from a person whenever they are triggered to perform any action in relation to their security system. Once you are able to make the right predictions, you will be able to get passwords and other valuable computer assets without having to use too many tools.
Answers
Social engineering is considered as both an art and a science. It is a form of hacking that involves the manipulation of victims through social interaction instead of directly breaking into a computer system.
The logic behind social engineering is simple, if one knows how to trick a person into giving out the data they need, they can easily access all the information and access they need with the least resistance possible. This makes social engineering a crucial part of hacking since it allows hackers to gain access to devices, accounts, or applications without making any additional effort.
By using social engineering tactics, a hacker can access a system without having to go through all the other hijacking tactics up their sleeve.The most challenging part of social engineering is securing trust, which is only possible by getting someone's trust. Hackers use various tactics to predict possible responses from a person whenever they are triggered to perform any action in relation to their security system.
The ability to read possible responses from a person is a significant skill for hackers since it enables them to predict passwords and other valuable computer assets without having to use too many tools. Successful hackers use social engineering as a powerful tool to penetrate a system.
In conclusion, social engineering is an essential component of hacking, and a significant part of its success lies in the art of manipulation.
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cylindrical specimen of this alloy 32 mm in diameter and 188 mm long is to be pulled in tension. Assume a value of 0.34 for Poisson's ratio. Calculate the stress (in MPa) necessary to cause a 0.0105 mm reduction in diameter.
Answers
Answer:
The answer is below
Explanation:
The poison ratio is given by the formula:
\(v=-\frac{\epsilon_x}{\epsilon_z} =-\frac{\epsilon_y}{\epsilon_z} \\\\Where\ \epsilon_y=transverse\ strain, \epsilon_z=longitudinal\ strain,v=poison\ ratio\\ \\The\ transverse\ strain(\epsilon_x)=\epsilon_y=\frac{change\ in\ diameter}{initial\ diameter}=\frac{\Delta d}{d_o} =\frac{-0.0105\ mm}{32\ mm} \\=-0.000328\\\\v=-\frac{\epsilon_x}{\epsilon_z} \\\\\epsilon_z=\frac{-\epsilon_x}{v} =\frac{-(-0.000328)}{0.34}\\ \\\epsilon_z=9.65*10^{-4}\)
We then locate the strain of 9.65 * 10⁻⁴ on the stress-strain curve, this gives a stress of 68.9 MPa
The stress required to cause a reduction of 0.0105mm on the alloy is 68.9MPa
Data Given;
d = 32mml = 188mmv = 0.34Δd = 0.0105mmTransverse StrainThe transverse strain of the cylindrical alloy is the ratio between the reduction in diameter to the actual diameter
\(E^x = \frac{\delta d}{d}\\ E^x = \frac{-0.0105}{32}\\ E^x = -0.00033\\ E^x = -3.3*10^-^4\)
Longitudinal StrainThe longitudinal strain is the ratio between the transverse strain to the Poisson's ratio.
\(E^y = \frac{-E^x}{v}\\ E^y = \frac{3.3*10^-^4}{0.34}\\ E^y = 0.00097 = 9.7 *10^-^4\)
Using the strain-stress graph of a cylindrical alloy, we would find the strain of 0.00097 around the stress of 68.9MPa
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An automobile having a mass of 1100 kg initially moves along a level highway at 120 km/h relative to the highway. It then climbs a hill whose crest is 80 m above the level highway and parks at a rest area located there. Use a reference with kinetic and potential energy each equal to zero for the stationary highway before the hill. Let g = 9.81 m/s^2.
For the automobile, determine its change in kinetic energy and its change in potential energy, both in kJ. For the automobile, determine its change in kinetic energy, in kJ.
a. -8594
b. -663.1
c. -6.63x10^5
d. 663.1
Answers
Answer:
\(-6111.11\ \text{kJ}\)
\(863.28\ \text{kJ}\)
Explanation:
m = Mass of automobile = 1100 kg
v = Velocity of car = 120 km/h = \(\dfrac{120}{3.6}\ \text{m/s}\)
h = Height of hill = 80 m
g = Acceleration due to gravity = \(9.81\ \text{m/s}^2\)
Change in kinetic energy
\(KE=\dfrac{1}{2}m(u^2-v^2)\\\Rightarrow KE=\dfrac{1}{2}\times 1100\times (0-(\dfrac{120}{3.6})^2)\\\Rightarrow KE=-611111.11\ \text{J}\)
Change in kinetic energy is \(-6111.11\ \text{kJ}\)
Change in potential energy is given by
\(PE=mgh\\\Rightarrow PE=1100\times 9.81\times 80\\\Rightarrow PE=863280\ \text{J}\)
The change in potential energy is \(863.28\ \text{kJ}\).
If you want to revise a sketch or a feature when using a 3D CAD program, how do you make a correction without using the undo function
Answers
Answer:
See explanation
Explanation:
Truthfully, this answer can vary depending on the CAD program you are choosing to use. Generally, you go to your model tree (this has been on the left hand side of the screen in all of the CAD software I have used) and click the sketch or feature to edit. In some programs this is a left click and in others this is a right click. When the feature is correctly selected a menu should appear with the option to edit feature/sketch/definition/etc. Select this option and you should be able to edit what you wanted to.
TRUE OR FALSE security implemented solely on a desktop or laptop computer is local security.
Answers
True. security implemented solely on a desktop or laptop computer is local security.
Security measures implemented solely on a desktop or laptop computer are considered local security. Local security refers to the protection and safeguards implemented at the individual device level to secure the data and resources stored on that particular device. This can include measures such as password protection, encryption, antivirus software, and firewall settings specific to the device. Local security focuses on securing the device itself and the data stored on it, rather than considering broader network or system-level security measures.
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A jointed arm robot can rotate on the following 6 axes?
Answers
Answer:
-x, +x, -y, +y, -z, +z
Explanation:
These are the 6 axes
if there is insufficient combustion air, the flame in an oil furnace will be ____.
Answers
If there is insufficient combustion air in an oil furnace, the flame will be incomplete and produce undesirable effects. When the right amount of combustion air is not supplied, it results in an imbalance between the air and fuel ratio. This situation is called incomplete combustion, and it leads to the flame becoming unstable, smoky, and inefficient.
The primary issue with insufficient combustion air is the production of carbon monoxide (CO), a dangerous and odorless gas that can cause health issues or even death in high concentrations. CO is produced when hydrocarbon fuels, like oil, do not burn completely due to a lack of oxygen. Moreover, the efficiency of the furnace decreases, as less heat is generated from the same amount of fuel. This can lead to higher energy costs and a less comfortable environment.
In addition, a smoky, sooty flame can cause soot buildup on heat exchanger surfaces and in the chimney, reducing the effectiveness of heat transfer and potentially creating a fire hazard. It's essential to ensure that an oil furnace has an adequate supply of combustion air to promote safe, efficient, and complete combustion. Regular maintenance and inspection of the furnace, ventilation system, and air intake can help prevent issues related to insufficient combustion air.
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1. Lift swing arm restraints are to be used only by non-experienced
employees, because they will prevent the vehicle from falling.
O
True
False
Answers
a commercial refrigerator with r-134a as the working fluid is used to keep the refrigerated space at -35 c by rejecting waste heat to cooling water that enters the condenser at 18 c at a rate of 0.25 kg/s and leaves at 26 c. the refrigerant enters the condenser at 1.2 mpa and 50 c and leaves at the same pressure subcooled by 6 c. if the compressor consumes 3.3 kw of power , determine (a) the mass flow rate of the refrigerant, b) the refrigerant load, c) the cop, and d) the minimum power input to the compressor for the same refrigeration load.
Answers
At 1.2mpa pressure and 50c
What is pressure?
By pressing a knife against some fruit, one can see a straightforward illustration of pressure. The surface won't be cut if you press the flat part of the knife against the fruit. The force is dispersed over a wide area (low pressure).
a)Mass flow rate of the refrigerant
Therefore h1= condenser inlet enthalpy =278.28KJ/Kg
saturation temperature at 1.2mpa is 46.29C
Therefore the temperature of the condenser
T2 = 46.29C - 5
T2 = 41.29C
Now,
d)power consumed by compressor W = 3.3KW
Q4 = QL + w = Q4
QL = mR(h1-h2)-W
= 0.0498 x (278.26 - 110.19)-3.3
=5.074KW
Hence refrigerator load is 5.74Kg
(COP)r = 238/53
(Cop) = 4.490
Therefore the above values are the (a) mass flow rate of the refrigerant, b) the refrigerant load, c) the cop, and d) the minimum power input to the compressor for the same refrigeration load.
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Project cost is ETB 30,000 and the cash inflows are ETB 10,000, the life of the project is 5
years. Calculate the pay-back period
Answers
The payback period is the length of time it takes for a project to recoup its initial cost. To calculate the payback period, we need to determine how many years it will take for the cash inflows to equal the initial project cost.
How to calculate payback period?
In this case, the project cost is ETB 30,000 and the annual cash inflows are ETB 10,000.
Payback period = Project cost / Annual cash inflows
Payback period = 30000/10000
Payback period = 3 years
It will take 3 years for the project to recoup its initial cost of ETB 30,000 with annual cash inflows of ETB 10,000.
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Which of the following best describes the difference between engineering and engineering technology?
a.
Engineering technology are the systems used in the development of engineering projects.
b.
Engineering is the application of engineering technology.
c
Engineering is focused on design and theory, while engineering technology focuses on application and troubleshooting.
Answers
Engineering is the application of scientific and mathematical principles to design and develop structures, machines, systems, and processes. Engineers use their knowledge of science, mathematics, and engineering principles to design, develop, and test new products and processes. They also analyze existing products and processes to identify areas for improvement.
On the other hand, engineering technology is the practical application of engineering principles in the workplace. Engineering technology professionals work in a hands-on capacity to solve technical problems, troubleshoot issues with machinery and systems, and improve production processes.
While both engineering and engineering technology involve the application of scientific and mathematical principles, engineering is focused on design and theory, while engineering technology focuses on application and troubleshooting. Engineers typically work in research and development, while engineering technology professionals work in industries such as manufacturing, construction, and transportation.
We have an amplifier that amplifies a 1 kHz signal from a detector. The load for this amplifier can be modelled as a 50 k resistor. The amplifier output has a large amount of 500 KHz noise. We need to reduce the amplitude of noise by a factor of 10. Design a first-order passive filter which car be/placed between the amplifier and the load. Calculate the value of signal attenuation due to the filter?
Answers
The signal attenuation due to the filter can be calculated by evaluating the magnitude of the transfer function at the signal frequency (1 kHz).
What is the value of signal attenuation caused by the first-order passive filter in the given amplifier setup?To design a first-order passive filter that reduces the amplitude of the 500 kHz noise by a factor of 10, we can use a low-pass filter configuration. The cutoff frequency of the filter should be set above the desired signal frequency (1 kHz) and below the noise frequency (500 kHz).
The transfer function of a first-order low-pass filter is given by H(s) = 1 / (1 + s/ωc), where s is the complex frequency variable and ωc is the cutoff frequency.
To calculate the value of signal attenuation due to the filter, we can evaluate the transfer function at the signal frequency (1 kHz). Let's assume the cutoff frequency ωc is chosen as 5 kHz for this example.
At the signal frequency (1 kHz), the transfer function becomes:
H(jωs) = 1 / (1 + jωs/ωc)
To find the signal attenuation, we need to calculate the magnitude of the transfer function at the signal frequency:
|H(jωs)| = |1 / (1 + jωs/ωc)|
By substituting ωs = 2πf = 2π × 1 kHz = 2π × 1000 rad/s and ωc = 2π × 5 kHz = 2π × 5000 rad/s into the transfer function, we can evaluate the magnitude and determine the signal attenuation.
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The Stefan-Boltzmann law can be employed to estimate the rate of radiation of energy H from a surface, as in
H = Aeσ^4
where H is in watts, A = the surface area (m^2 ), e = the emissivity that characterizes the emitting properties of the surface (dimensionless), σ = a universal constant called the Stefan-Boltzmann constant (= 5.67 x 10^8 W m^2 K^-4 ), and T = absolute temperature (K).
Required:
Determine the error of H for a steel plate with A = 0.15 m^2 , e = 0.90, and T 5 650 ± 20.
b. Compare your results with the exact error. Repeat the computation but with T = 650 ± 40. Interpret your results.
Answers
Explanation:
A.
H = Aeσ^4
Using the stefan Boltzmann law
When we differentiate
dH/dT = 4AeσT³
dH/dT = 4(0.15)(0.9)(5.67)(10^-8)(650)³
= 8.4085
Exact error = 8.4085x20
= 168.17
H(650) = 0.15(0.9)(5.67)(10^-8)(650)⁴
= 1366.376watts
B.
Verifying values
H(T+ΔT) = 0.15(0.9)(5.67)(10)^-8(670)⁴
= 1542.468
H(T+ΔT) = 0.15(0.9)(5.67)(10^-8)(630)⁴
= 1205.8104
Error = 1542.468-1205.8104/2
= 168.329
ΔT = 40
H(T+ΔT) = 0.15(0.9)(5.67)(10)^-8(690)⁴
= 1735.05
H(T-ΔT) = 0.15(0.9)(5.67)(10^-8)(610)⁴
= 1735.05-1059.83/2
= 675.22/2
= 337.61
A bar of mild steel has a diameter of 75 mm and is placed inside a hollow aluminum cylinder ofinternal diameter 75 mmand external diameter 100 mm; both bar and cylinder are the same length. Theresulting composite bar is subjected to an axial compressive load of 1000 kN. If the bar and cylindercontract by the same amount, calculate the stress in each. The temperature of the compressed compositebar is then reduced by 150Cbut no change in length is permitted. Calculate the final stress in the bar and the cylinder if E(steel)= 200,000 N/mm^2, E(aluminum)= 80,000 N/mm^2, coefficient of linear expansion for steel= 0. 0000012/C and coefficient of linear expansion for aluminum= 0. 000005/C
Answers
According to the question: the Stress in cylinder is 1813 N/mm^2.
What is cylinder?A cylinder is a three-dimensional geometric shape with two circular bases, one at each end, connected by a curved surface. The curved surface is a straight line connecting the two circular bases and is called the side or lateral surface. The two circular surfaces that make up the cylinder are called the bases.
The initial stress in the bar and cylinder can be calculated using the following equation:
Stress = Load / (Area of bar x Area of cylinder)
Stress in bar = 1000 kN / (π*(75/2)^2 * π*(75/2)^2) = 2300 N/mm^2
Stress in cylinder = 1000 kN / (π*(75/2)^2 * π*(100/2)^2) = 1875 N/mm^2
The final stress in the bar and cylinder can be calculated using the following equation:
Stress = (Load + Change in Length * Modulus of Elasticity * Coefficient of Linear Expansion * Change in Temperature) / (Area of bar* Area of cylinder)
Stress in bar = (1000 kN + (75 mm * 200000 N/mm^2 * 0.0000012/C * -150C)) / (π*(75/2)^2 * π*(75/2)^2) = 2250 N/mm^2
Stress in cylinder = (1000 kN + (75 mm * 80000 N/mm^2 * 0.000005/C * -150C)) / (π*(75/2)^2 * π*(100/2)^2) = 1813 N/mm^2
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the sequence that begins with 2 and in which each successive term is 3 more than the preceding term. the first 10 terms are
Answers
The first 10 terms of the given sequence are:
2, 5, 8, 11, 14, 17, 20, 23, 26, 29.
How to solve sequence?The given sequence starts with 2 and each successive term is 3 more than the preceding term.
So, the first term is 2.
The second term is 2 + 3 = 5.
The third term is 5 + 3 = 8.
The fourth term is 8 + 3 = 11.
The fifth term is 11 + 3 = 14.
The sixth term is 14 + 3 = 17.
The seventh term is 17 + 3 = 20.
The eighth term is 20 + 3 = 23.
The ninth term is 23 + 3 = 26.
The tenth term is 26 + 3 = 29.
So the first 10 terms of the given sequence are:
2, 5, 8, 11, 14, 17, 20, 23, 26, 29
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Cold water at 20 degrees C and 5000 kg/hr is to be heated by hot water supplied at 80 degrees C and 10,000 kg/hr. You select from a manufacturer's catalog a shell-and-tube heat exchanger (one shell with two tube passes) having a UA value of 11,600 W/K. Determine the hot water outlet temperature.
Answers
Answer:
59°C
Explanation:
Given that, Cc = McCp,c = 5000 /3600 × 4178 = 5803.2(W/K)
and Ch = MhCp,h = 10000 / 3600 × 4188 = 11634.3(W/K)
Therefore the minimum and maximum heat capacities are:
Cmin = Cc = 5803.2(W/K)
Cmax = Ch = 11634.3(W/K)
The capacity ratio is:
Cr = Cmin / Cmax = 0.499 = 0.5
The maximum possible heat transfer rate is:
Qmax = Cmin (Th,i - Tc,i) = 5803.2 (80 - 20) = 348192(W)
And the number of transfer units is: NTU = UA / Cmin = 11600 / 5803.2 = 1.99
Given that from the appropriate graph in the handouts we can read = 0.7. So the actual heat transfer rate is: Qact = Qmax = 0.7 × 348192 = 243734.4(W)
Hence, the outlet hot temperature is: Th,o = Th,i - Qact / Ch = 59°C
under alleys, driveways, highways, parking lots, roads, and streets, what is the minimum burial depth in inches for wiring in intermediate metal conduit or rigid metal conduit?
Answers
Under alleys, driveways, highways, parking lots, roads, and streets, the minimum burial depth in inches for wiring in intermediate metal conduit or rigid metal conduit is 18 inches.
`It is important to have the wiring installed underground at a safe depth to prevent accidents and damage. The National Electrical Code (NEC) specifies the minimum burial depth for electrical wiring, which varies depending on the location and type of wiring. For underground electrical wiring, the minimum burial depth is generally 18 inches for intermediate metal conduit or rigid metal conduit. This depth ensures that the wiring is safe from damage by digging and other activities. However, the burial depth may be higher if the wiring is installed under a structure or if there are other local codes or regulations that require it. It is always important to consult the local codes and regulations before installing any electrical wiring to ensure that it is done safely and in compliance with the applicable standards.
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