A very long rectangular fin is attached to a flat surface such that the temperature at the end of the fin is essentially that of the surrounding air, i.e. 20C. Its width is 5 cm; thickness is 1 mm; thermal conductivity is 200 W/m.K; and base temperature is 40C. The heat transfer coefficient is 22 W/m2 .K. Estimate the temperature at a distance of 5 cm from the base and the rate of heat loss from the entire fin.

Answers

Answer 1

Answer:

The answer is below

Explanation:

Given that:

x = 5 cm = 0.05 m, width (w) = 5 cm = 0.05 m, thickness (t) = 1 mm = 0.001 m, k = thermal conductivity = 200 W/mK, h = heat transfer coefficient = 22 W/m².K, Tb = base temperature = 40°C, T∞ = 20°C

[tex]m=\sqrt{ \frac{hp}{kA} }=\sqrt {\frac{22*(2*0.05+2*0.001)}{200*(0.05*0.001)}} =15\ m^{-1}\\\\\frac{T-T_{\infty}}{T_b-T_{\infty}} =e^{-mx}\\\\\frac{T-20}{40-20} =e^{-15*0.05}\\\\T-20=9.45\\\\T=29.45^oC\\\\The\ rate\ of\ heat\ loss\ is:\\\\\dot{Q}=\sqrt{hpkA}(T_b-T_{\infty})\\ \\\dot{Q}=\sqrt{22*(2*0.05+2*0.001)*200*0.05*0.001}*(40-20)\\\\\dot{Q}=3\ W[/tex]


Related Questions

A car makes a hissing noise each time the A/C system and engine are turned off. Technician A says that the noise is caused by a refrigerant leak. Technician B says that the noise is caused by equalization of system pressures. Who is correct?

Answers

Answer:

It's equalization of the system

Explanation: If there was a leak it would likely leak all the time even if the car was turned off. Plus, a system leak bad enough to hear would drain the system of refrigerant very quickly and would no longer cool.

A commercial jet is flying at a standard altitude of 35,000 ft with a velocity of 550 mph: (a) what is the Mach number? (b) should the flow be treated as incompressible, why or why not?

Answers

Answer:

Mach number = 0.68168

The flow should be treated as compressible.

Explanation:

Given that:

The altitude of a commercial jet = 35000

The properties of air at that given altitude are as follows:

Pressure = 24.577 kPa

Temperature T = 50.78176° C

Temperature T = ( 50.78176 + 273 )K = 328.78176 K

[tex]\varphi = 0.38428 \ kg/m^3[/tex]

The velocity is also given as: 550 mph = 245.872 m/s

Therefore, the sonic velocity is firstly determined by using the formula:

[tex]a = \sqrt{ \vartheta \times R \times T\[/tex]

[tex]a = \sqrt{1.4 \times 287 \times 323.78176[/tex]

[tex]a = \sqrt{130095.5112[/tex]

a = 360.68755 m/s

Then, we can calculate the Mach number by using the expression:

[tex]{Mach \ number = \dfrac{V}{a}}[/tex]

[tex]Mach \ number = \dfrac{245.872}{360.68755}[/tex]

Mach number = 0.68168

b) Ideally, all flows are compressible because the Mach number is greater than 0.3, suppose the Mach number is lesser than 0.3, then it is incompressible.

What is the stress term called which is a measure of the stiffness or resistance to deflection?
Modulus of Elasticity (E)
Extreme Fiber Bending (F )
Horizontal Shear Parallel to the Grain (F //)
Compression Perpendicular to the Grain (F z )

Answers

Answer:Modulus of Elasticity (E)-------- A

Explanation:

The modulus of elasticity, Young's modulus E is a measure of a material's stiffness or resistance to being elastically deformed when stressed or due to tension According to  Hook's law the modulus of elasticity is defined as the ratio of the stress to the strain and defined as the slope of its stress-strain region  in the stress and strain graph.

--The stiffer a material, the higher the elastic modulus and vice versa for a less stiff material.

it can be calculated with this formulae

Young’s modulus equation is E = tensile stress/tensile strain

= (FL) / (A X change in L)

where F = applied force,

L = initial length,

A = square area,

E = Young’s modulus in Pascals (Pa).

It is desired to enrich the partial pressure of hydrogen in a hydrogen–nitrogen gas mixture for which the partial pressures of both gases are 0.1013 MPa (1 atm). It has been proposed to accomplish this by passing both gases through a thin sheet of some metal at an elevated temperature; in as much as hydrogen diffuses through the plate at a higher rate than does nitrogen, the partial pressure of hydrogen will be higher on the exit side of the sheet. The design calls for partial pressures of 0.051 MPa (0.5 atm) and 0.01013 MPa (0.1 atm), respectively, for hydrogen and nitrogen. The concentrations of hydrogen and nitrogen (CHC
H and CNC N , in mol/m3mol/m
3 ) in this metal are functions of gas partial pressures (pH2 and pN2p
H 2 and p N , in MPa) and absolute temperature and are given by the following expressions:
CH=2.5×103√pH2exp(−27,800J/mol/RT)
CN=2.75×103√pN2exp(−37,600J/mol/RT )
​Furthermore, the diffusion coefficients for the diffusion of these gases in this metal are functions of the absolute temperature, as follows:
DH(m2/s)=1.4×10−7exp(−13,400J/mol/RT)
DN(m2/s)=3.0×10−7exp(−76,150J/mol/RT)
Is it possible to purify hydrogen gas in this manner? If so, specify a temperature at which the process may be carried out, and also the thickness of metal sheet that would be required. If this procedure is not possible, then state the reason(s) why.

Answers

Answer:

T = 3460 K

Explanation:

See attachment for calculation.

Since the temperature we have is above the melting point of the metal, then we can conclude that it is too high for the diffusion process to be possible.

due at 11:59pm please help

Which of the items shown in the photo were developed using engineering design processes to develop a solution to a problem?

A. computer
B. coffee cup
C. table
D. pen

An engineer proposes that a newly developed chemical could be sprayed from aircraft to slow the rate of burning in a forest fire. What is the next step the engineer is likely to take to develop a solution to fighting forest fires?

A. test a number of similar chemicals

B. spray and compare the effectiveness of each tested chemical to water.

C. add the chemical to all aircraft spray tanks.

D. design a spray system for the chemical.

Answers

I believe it’s c table

Explain and justify which type of model to use in the final design phase to present to a client.

Answers

Answer:

Visualization model

Explanation:

This type of model uses a computer to analyze and simulate data that require processing to enable presentation to users in a meaningful manner where even a layman could have a clue and understand the results expected. Through this model, results are presented in various forms such as plots of a the results against time for displaying relationships. For example a model that uses an animation could display results in various dimensions such as 2D and 3D ,and position in terms of orientation and position in respect to time.

Answer:

The correct answer is a prototype.

Explanation:

The prototype should be fully functional in order to test out the design, but aesthetics do not necessarily need to be considered yet. The prototype can allow constructive feedback from the client and team members, and it can be smaller than the eventual finished product. It can be used to “sell” an idea to a client.

A concrete batch plant has a batching chamber capacity of 12.5 cy and an average batching cycle time of 3 min. Plant efficiency is 84%. What is the estimated batching production in cy/hr?

Answers

Answer:

The estimated batching production is 210 cy/hr

Explanation:

Given;

capacity of the batching chamber of the plant, Q = 12.5 cy

average batching cycle time, t = 3 min

plant efficiency, n = 84 %

The estimated batching production is calculated as efficiency of the machine multiplied by the production rate in hour. This is given by the solution below;

Batching production = (nQ )/ t

[tex]Batching \ production = 0.84(\frac{12.5 \ cy}{3 \ min} *\frac{60 \ min}{1 \ hr})\\\\ Batching \ production = 210 \ cy/hr[/tex]

Therefore, the estimated batching production is 210 cy/hr

Realiza las siguientes conversiones.

4 Hm2 a Dm2=_______________

21345 Cm2 a M2=_____________

0,592 Km2 a M2=______________

0,102 M2 a Cm2=______________

23911 Km2 a Hm2=_____________

Answers

Answer:

a) 4 hectómetros cuadrados equivalen a 400 decámetros cuadrados.

b) 21345 centímetros cuadrados equivalen a 2,135 metros cuadrados.

c) 0,592 kilómetros cuadrados equivalen a 592000 metros cuadrados.

d) 0,102 metros cuadrados equivalen a 1020 centímetros cuadrados.  

e) 23911 kilómetros cuadrados equivalen 2391100 hectómetros cuadrados.

Explanation:

a) 4 hectómetros cuadrados a decámetros cuadrados:

Según las unidades de área y sus escalas utilizadas por el Sistema Internacional de Pesos y Medidas, un hectómetro cuadrado equivale a 100 decámetros cuadradps. Entonces, obtenemos el dato equivalente por la siguiente regla de tres simple:

[tex]x = 4\,Hm^{2}\times\frac{100\,Dm^{2}}{1\,Hm^{2}}[/tex]

[tex]x = 400\,Dm^{2}[/tex]

4 hectómetros cuadrados equivalen a 400 decámetros cuadrados.

b) 21345 centímetros cuadrados a metros cuadrados:

Según las unidades de área y sus escalas utilizadas por el Sistema Internacional de Pesos y Medidas, un metro cuadrado equivale a 10000 centímetros cuadrados. Entonces, obtenemos el dato equivalente por la siguiente regla de tres simple:

[tex]x = 21345\,cm^{2}\times \frac{1\,m^{2}}{10000\,cm^{2}}[/tex]

[tex]x = 2,135\,m^{2}[/tex]

21345 centímetros cuadrados equivalen a 2,135 metros cuadrados.

c) 0,592 kilómetros cuadrados a metros cuadrados:

Según las unidades de área y sus escalas utilizadas por el Sistema Internacional de Pesos y Medidas, un kilómetro cuadrado equivale a 1000000 metros cuadrados. Entonces, obtenemos el dato equivalente por la siguiente regla de tres simple:

[tex]x = 0,592\,km^{2}\times \frac{1000000\,m^{2}}{1\,km^{2}}[/tex]

[tex]x = 592000\,m^{2}[/tex]

0,592 kilómetros cuadrados equivalen a 592000 metros cuadrados.

d) 0,102 metros cuadrados a centímetros cuadrados:

Según las unidades de área y sus escalas utilizadas por el Sistema Internacional de Pesos y Medidas, un metro cuadrado equivale a 10000 centímetros cuadrados. Entonces, obtenemos el dato equivalente por la siguiente regla de tres simple:

[tex]x = 0,102\,m^{2}\times \frac{10000\,cm^{2}}{1\,m^{2}}[/tex]

[tex]x = 1020\,cm^{2}[/tex]

0,102 metros cuadrados equivalen a 1020 centímetros cuadrados.

e) 23911 kilómetros cuadrados a hectómetros cuadrados:

Según las unidades de área y sus escalas utilizadas por el Sistema Internacional de Pesos y Medidas, un kilómetro cuadrado equivale a 100 hectómetros cuadrados. Entonces, obtenemos el dato equivalente por la siguiente regla de tres simple:

[tex]x = 23911\,km^{2}\times \frac{100\,Hm^{2}}{1\,km^{2}}[/tex]

[tex]x = 2391100\,Hm^{2}[/tex]

23911 kilómetros cuadrados equivalen 2391100 hectómetros cuadrados.

inspections may be_____ or limited to a specific area such as electrical or plumbing
A. Metering
B. General

Answers

A is the answer for the sentence

Facts about cellphones

Answers

Answer:

Your mobile phone has more computing power than the computers used for the Apollo 11 moon landing.

Mobile phones have to “work harder” to get a signal if you are in a moving vehicle.

The first mobile phone was made in 1973.

The first mobile phones that went on sale in 1983 cost nearly $4,000 each.

In 2012 Apple sold 340,000 phones per day.

4 out of 10 Brits admit to snooping on their partners phone.

Out of the 53% of snoopers that found incriminating evidence on their partner’s phone, 5% went on to terminate their relationship.

Waterproof mobile phones came to market because Japanese youngsters like to use them in the shower.

Apparently mobile phones have 18 times more bacteria on them than toilet handles!

Phubbing describes the act of snubbing someone by using your mobile phone in their company.

In 2015 more people died from taking selfies than shark attacks.

Teenagers that use a phone more than 2 hours a day increase their risk of depression and anxiety.

Nomobophobia is severe anxiety caused by the thought or act of losing your phone or running out of battery.

Explanation:

What are the ordinary and absolute temperature scales in the SI and the English system?

Answers

Answer:

The answer is below

Explanation:

Absolute temperature is the temperature of a body with reference to 0 as the absolute zero.

English system of measurement are measurements used in united states while the S.I units are units that are universally accepted.

The temperature scale in S.I are Celsius (°C) for ordinary temperature and kelvin(K) for absolute temperature while the temperature scale in English system is Fahrenheit (°F) for ordinary temperature and Rankine (R) for absolute temperature.

The information regarding the ordinary and absolute temperature scales in the SI and the English system is as follows:

Absolute temperature is the temperature of a body with reference to 0 as the absolute zero. English system of measurement are measurements that are used in united states while the S.I units are units that are universally accepted. The temperature scale in S.I are Celsius (°C) for ordinary temperature and kelvin(K) for absolute temperature while the temperature scale in English system is Fahrenheit (°F) for ordinary temperature and Rankine (R) for absolute temperature.

Learn more: brainly.com/question/17429689

what are the two safety precautions taken before driving a car​

Answers

Answer:

1. Check mirrors2. Put on your seat belt

Explanation:

1. Checking your mirrors are very important because if someone screwed with them then it can mess up your driving.

2. Putting on your seat belt is a law so you must put it on and it can save your life one day.

The critical resolved shear stress for a metal is 36 MPa. Determine the maximum possible yield strength (in MPa) for a single crystal of this metal that is pulled in tension.

Answers

Answer:

72 MPa

Explanation:

Critical resolved shear stress = 36 MPa

calculate the maximum possible yield strength for a single crystal of the metal

first we have to express the critical resolved shear stress as

бy = 2т[tex]_{critical}[/tex]

given that the minimum stress needed to introduce yielding curve will occur  at Ψ = λ = 45

where : бy = yielding stress

             t[tex]_{critical}[/tex] = 36MPa

therefore the maximum possible yield strength

= (2) * (36)

= 72 MPa

I need help on this ASAP PLZ?

Answers

Answer:

Explanation:

7. False

8. True

9. True

10.True

11. True

To determine if a product or substance being used is hazardous, consult:__________.

a. A dictionary

b. An MSDS

c. SAE standards

d. EPA guidelines

Answers

Answer:

Option B: An MSDS

Explanation:

A dictionary is used to check up the meaning of general words and not for checking if a substance being used is hazardous. Option A is wrong.

MSDS means "Material Safety Data Sheet" and it contains documents with information that relates to occupational health & safety for checking various substances and products. Thus, option B is correct.

SAE stands for Society of Automotive Engineering and their standards pertain to mainly Automobiles. Thus option C is wrong.

EPA guidelines are mainly for checking facility and environmental health and safety compliance. Thus, option D is wrong.

A hypothetical metal has the simple cubic (SC) crystal structure. If its atomic weight is 70.4 g/mol and the atomic radius is 0.126 nm. Compute its density (in g/cm3)

Answers

Answer:

[tex]7304g/cm^3[/tex]

Explanation:

Density is the mass per unit volume, it is usually measured in kg/m³.

The density of a crystal structure is given by:

[tex]\rho=\frac{mass\ of\ atoms\ in\ unit\ cell}{volume\ unit\ cell} =\frac{nA}{V_cN_A} \\\\\rho=density, n= number\ of\ atoms/unit=1\ atom/unit\ cell,A=atomic\ weight=70.4\ g/mol,N_A=avogadro\ constant=6.023*10^{23}atoms/mol,V=volume=2R^3=[2(0.126*10^{-8})]^3cm\\\\\rho=\frac{1*70.4}{[2(0.126*10^{-8})]^3*6.023*10^{23}} =7304g/cm^3[/tex]

Answer:

7.307g/cm^3

Explanation:

The other guy is mostly right but his conversion factor was off. It should be 1.26x10^-8 on the bottom

Legal metrology would protect consumers from businesses that do not take measurements according to defined measuring regulations.

Answers

From what my research concluded, true

Za answa iz:

True

Twust meh

Should transistors used in switching circuits be biased in the active region? Why or why not?

Answers

Answer:

  no

Explanation:

No. More power is dissipated when the transistor is in its active region. In general, transistors in switching circuits are biased either "on" or "off". Time spent in the active region is minimized.

_____

On the other hand, speed can be enhanced if the transistors are active. So, it's a speed/power trade-off. Usually power is of more interest, particularly when there are millions of switching circuits. However, in certain applications, speed may be the priority, so the transistor will be biased in its active region.

(TCO 7) Find the resolution of the Fourier transform if a signal is sampled at 16,384 samples/second and we collect a total of 8,192 data points and then apply the FFT algorithm to them.

Answers

Answer:

Resolution of Fourier transform = 2Hz

Explanation:

Given:

Sample signals = 16,384 samples/second

Number of data points = 8,192 oints

Find:

Resolution of Fourier transform

Computation:

Resolution of Fourier transform = fs / N

Resolution of Fourier transform = 16,384 / 8,192

Resolution of Fourier transform = 2Hz

What is the meaning of *binuhat lakas nang loob na ibinaon

Answers

Answer:

carried courage buried

Explanation:

its Filipino

gasoline has a comparatively high btu per galloon rating around?

Answers

Answer:

116,090 Btus

Explanation:

How are weather and climate different

Answers

Answer:

- weather refers to short-term changes in the atmosphere

- climate describes what the weather is like over a long period of time in one area.

Two vehicles collided head on while traveling on a curve tangent with a 3% grade. Vehicle V1 skidded 195 feet downhill before colliding with vehicle V2. Vehicle V2 skidded 130 feet. The police report estimates that the speed of both vehicles at impact was 25 mph, based on vehicle deformation. Assume a coefficient of friction of 0.48. What is V1 speed at the beginning of the skid?

Answers

Answer:

Speed V1 at the beginning of the skid  = 57.075 mph

Explanation:

Calculate the V1 speed at the beginning of the skid

V1 ( speed before brake was applied ) = ?

distance travelled by Vehicle 1 = 195 ft

curve tangent for vehicle 1 =  - 3% = - 0.03

coefficient of friction = 0.48

speed at Impact = 25 mph

To determine the V1 speed at the beginning of the skid we have to apply AASTHO

d1 = [tex]( \frac{VA^{2} - VA^{12} }{30(F+N)} )[/tex]

195 =  [tex](\frac{VA^2- 25^2}{30(0.48-0.03)} )[/tex]

Hence : VA = 57.075 mph

Estimate the rotor inertia assuming that the rotor is a cylinder of radius 8.98 mm, and length 25 mm, with a material of 100% copper. Explain why the rotor inertia may differ from these assumptions?

Answers

Answer:

The moment of inertia of the rotor is approximately [tex]1.105\times 10^{-6}[/tex] kilogram-square meters.

The rotor inertia may differ from these assumption due to differences in the shape of cross section.

Explanation:

We assume that rotor can be represented as a solid cylinder of radius [tex]r[/tex], length [tex]l[/tex], made of cooper ([tex]\rho = 8960\,\frac{kg}{m^{3}}[/tex]) and whose axis of rotation passes through its center of mass and is parallel to its cross section. By definition of Moment of Inertia and Theorem of Parallel Axes, the moment of inertia of the rotot is:

[tex]I = \frac{1}{4}\cdot \rho \cdot \left(\frac{\pi}{4} \right) \cdot R^{3}\cdot (3\cdot R^{2}+L^{2})[/tex]

[tex]I = \frac{\pi}{16}\cdot \rho \cdot R^{3}\cdot (3\cdot R^{2}+L^{2})[/tex] (Eq. 1)

Where:

[tex]\rho[/tex] - Density of copper, measured in kilograms per cubic meter.

[tex]R[/tex] - Radius of the rotor, measured in meters.

[tex]L[/tex] - Length of the rotor, measured in meters.

[tex]I[/tex] - Moment of inertia, measured in kilogram-square meters.

If we know that [tex]\rho = 8960\,\frac{kg}{m^{3}}[/tex], [tex]L = 25\times 10^{-3}\,m[/tex] and [tex]R = 8.98\times 10^{-3}\,m[/tex], the estimated moment of inertia of the rotor is:

[tex]I = \frac{\pi}{16}\cdot \left(8960\,\frac{kg}{m^{3}} \right)\cdot (8.98\times 10^{-3}\,m)^{3}\cdot [3\cdot (8.98\times 10^{-3}\,m)^{2}+(25\times 10^{-3}\,m)^{2}][/tex]

[tex]I \approx 1.105\times 10^{-6}\,kg\cdot m^{2}[/tex]

The moment of inertia of the rotor is approximately [tex]1.105\times 10^{-6}[/tex] kilogram-square meters.

From D'Alembert's Formula we know that net force of rigid bodies experimenting rotation equals the product of moment of inertia and angular acceleration. In this case, the purpose is minimizing moment of inertia and it is done by modifying the shape of the cross section so that rotor could be aerodynamically more efficient.

Recently, due to rapid urbanization and mechanization residents of a city are suffering from harmful effects of the ultra violet rays. Depletion of which layer is likely to have led to this situation

Answers

Depletion of the ozone layer is the cause of harmful ultra violet rays

Use the following clues to help fill in the chart on the next page. Put an X in the spaces that are INCORRECT and Highlight the
CORRECT
1 The wizard with the lavender wand is in Ravenel or Sparrowan, and earned 50 or 60 points
2. Gorgonscale earned 10 points less than Sparrowman
3 Lynn scored 20 points less than the wizard with the incense wand.
4. Timmy scored 70 or 80 points. He is in Gorgonscale or Hydraden
5. Among Bennie and the wizard from Sparrowan, one earned 70 points and the other has the lavender wand.
6. The mandragore wand belongs to Edward or to the House of Hydraden
7 Ravenel didn't earn 60 points and Edward is not among it's wizards
8. Bennie scored 10 points more than Edward
9. The wizard with the mandragore wand didn't earn 70 points.

Answers

The wizard with the lavender wand is in Ravenel or Sparrowan, and earned 50 or 60 points

Your company is planning to build a pipeline to transport gasoline from the refinery to a field of storage tanks. The parameters for the prototype system are a pipe diameter of 1 m, with a flow velocity of 0.5 m/s at 25°C. The model system will use water at STP with a geometric scaling factor of 1 : 20. What fluid velocity is required in the model system to guarantee kinematic similarity in the form of equal Reynolds numbers?

Answers

Answer:

The model system will need water flowing at a velocity of 2.07 meters per second to guarantee kinematic similarity in the form of equal Reynolds numbers.

Explanation:

The Reynolds number ([tex]Re_{D}[/tex]) is a dimensionless criterion use for flow regime of fluids, which is defined as:

[tex]Re_{D} = \frac{\rho \cdot v\cdot D}{\mu}[/tex] (Eq. 1)

Where:

[tex]\rho[/tex] - Density, measured in kilograms per cubic meter.

[tex]\mu[/tex] - Dynamic viscosity, measured in kilograms per meter-second.

[tex]v[/tex] - Average flow velocity, measured in meters per second.

[tex]D[/tex] - Pipe diameter, measured in meters.

We need to find the equivalent velocity of water used in the prototype system. In this case, we assume that [tex]Re_{D,gas} = Re_{D,w}[/tex]. That is:

[tex]\frac{\rho_{w}\cdot v_{w}\cdot D_{w}}{\mu_{w}} = \frac{\rho_{gas}\cdot v_{gas}\cdot D_{gas}}{\mu_{gas}}[/tex] (Eq. 2)

Where subindex [tex]w[/tex] is used for water and [tex]gas[/tex] for gasoline.

If we know that [tex]\rho_{gas} = 690\,\frac{kg}{m^{2}}[/tex], [tex]\mu_{gas} = 0.006\,\frac{kg}{m\cdot s}[/tex], [tex]v_{gas} = 0.5\,\frac{m}{s}[/tex], [tex]D_{gas} = 1\,m[/tex], [tex]\rho_{w} = 1000\,\frac{kg}{m^{3}}[/tex], [tex]\mu_{w} = 0.0018\,\frac{kg}{m\cdot s}[/tex] and [tex]D_{w} = 0.05\,m[/tex], then we get the following formula:

[tex]57500 = 27777.778\cdot v_{w}[/tex]

The fluid velocity for the prototype system is:

[tex]v_{w} = 2.07\,\frac{m}{y}[/tex]

The model system will need water flowing at a velocity of 2.07 meters per second to guarantee kinematic similarity in the form of equal Reynolds numbers.

How natural gas works and operates?
PLEASE HELP!!!

Answers

A molecule of natural gas is made up of carbon and hydrogen. When the hydrogen is segregated from the carbon and filled into a fuel cell, it fuses with oxygen to produce water, electricity, and heat. The carbon is released as carbon dioxide in smaller quantities than from gas turbines

A 30-mm-diameter shaft, made of AISI 1018 HR steel, transmits 10 kW of power while rotating at 200 rev/min. Assume any bending moments present in the shaft to be negligibly small compared to the torque. Determine the static factor of safety based on:a) The maximum-shear-stress failure theory.b) The distortion-energy failure theory.

Answers

Answer:

a) According to the maximum-shear-stress failure theory, the static factor of safety of the shaft is 2.440.

b) According to the distortion-energy failure theory, the static factor of safety of the shaft is 2.816.

Explanation:

First, we need to determine the torque experimented by the shaft ([tex]T[/tex]), measured in kilonewton-meters, whose formula is described:

[tex]T = \frac{\dot W}{\omega}[/tex] (Eq. 1)

Where:

[tex]\dot W[/tex] - Power, measured in kilowatts.

[tex]\omega[/tex] - Angular velocity, measured in radians per second.

If we know that [tex]\dot W = 10\,kW[/tex] and [tex]\omega = 20.944\,\frac{rad}{s}[/tex], then the torque experimented by the shaft:

[tex]T = \frac{10\,kW}{20.944\,\frac{rad}{s} }[/tex]

[tex]T =0.478\,kN\cdot m[/tex]

Let consider that shaft has a circular form, such that shear stress is determined by the following formula:

[tex]\tau = \frac{16\cdot T}{\pi\cdot D^{3}}[/tex] (Eq. 2)

Where:

[tex]D[/tex] - Diameter of the shaft, measured in meters.

[tex]\tau[/tex] - Torsional shear stress, measured in kilopascals.

If we know that [tex]D = 0.03\,m[/tex] and [tex]T =0.478\,kN\cdot m[/tex], the torsional shear stress is:

[tex]\tau = \frac{16\cdot (0.478\,kN\cdot m)}{\pi\cdot (0.03\,m)^{3}}[/tex]

[tex]\tau \approx 90164.223\,kPa[/tex]

a) According to the maximum-shear-stress failure theory, we get that maximum shear stress limit is:

[tex]S_{ys} = 0.5\cdot S_{ut}[/tex] (Eq. 3)

Where:

[tex]S_{ys}[/tex] - Ultimate shear stress, measured in kilopascals.

[tex]S_{ut}[/tex] - Ultimate tensile stress, measured in kilopascals.

If we know that [tex]S_{ut} = 440\times 10^{3}\,kPa[/tex], the ultimate shear stress of the material is:

[tex]S_{ys} = 0.5\cdot (440\times 10^{3}\,kPa)[/tex]

[tex]S_{ys} = 220\times 10^{3}\,kPa[/tex]

Lastly, the static factor of safety of the shaft ([tex]n[/tex]), dimensionless, is:

[tex]n = \frac{S_{ys}}{\tau}[/tex] (Eq. 4)

If we know that [tex]S_{ys} = 220\times 10^{3}\,kPa[/tex] and [tex]\tau \approx 90164.223\,kPa[/tex], the static factor of safety of the shaft is:

[tex]n = \frac{220\times 10^{3}\,kPa}{90164.223\,kPa}[/tex]

[tex]n = 2.440[/tex]

According to the maximum-shear-stress failure theory, the static factor of safety of the shaft is 2.440.

b) According to the distortion-energy failure theory, we get that maximum shear stress limit is:

[tex]S_{ys} = 0.577\cdot S_{ut}[/tex] (Eq. 5)

If we know that [tex]S_{ut} = 440\times 10^{3}\,kPa[/tex], the ultimate shear stress of the material is:

[tex]S_{ys} = 0.577\cdot (440\times 10^{3}\,kPa)[/tex]

[tex]S_{ys} = 253.88\times 10^{3}\,kPa[/tex]

Lastly, the static factor of safety of the shaft is:

[tex]n = \frac{253.88\times 10^{3}\,kPa}{90164.223\,kPa}[/tex]

[tex]n = 2.816[/tex]

According to the distortion-energy failure theory, the static factor of safety of the shaft is 2.816.

Nicole designs the hardware configuration of workstations that will be deployed to a newly formed company. She sets up the networking capabilities and policies that will govern the workstations when connected to the company network. What is her role in her company?

Answers

Answer:

a Network Engineer (architect)

Explanation:

Indeed, as a Network Engineer, we would expect Nicole to be in charge of planning, setting up, and managing the software and hardware components of the computer networks so that they function as intended.

A Network Engineer therefore would be responsible for setting up the networking capabilities and policies that will govern the workstations when connected to the company network.

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