A square aluminum plate 5 mm thick and 150 mm on a side is heated while vertically suspended in quiescent air at 75°c. determine the average heat transfer coefficient for the plate when its temperature is 15°c by two methods: using results from the similarity solution to the boundary layer equations, and using results from an empirical correlation.
By using the boundary layer equation, the average heat transfer coefficient for the plate is equal to 4.87 W/m²k.
Given the following data:
Surface temperature = 15°C
Bulk temperature = 75°C
Side length of plate = 150 mm to m = 0.15 meter.
How to calculate the average heat transfer coefficient.Since we have a quiescent room air and a uniform pole surface temperature, the film temperature is given by:
[tex]T_f=\frac{T_{s} + T_{\infty} }{2} \\\\T_f=\frac{15 + 75 }{2} \\\\T_f = 45[/tex]
Film temperature = 45°C to K = 273 + 45 = 318 K.
For the coefficient of thermal expansion, we have:
[tex]\beta =\frac{1}{T_f} \\\\\beta =\frac{1}{318}[/tex]
From table A-9, the properties of air at a pressure of 1 atm and temperature of 45°C are:
Kinematic viscosity, v = [tex]1.750 \times 10^{-5}[/tex] m²/s.Thermal conductivity, k = 0.02699 W/mk.Thermal diffusivity, α = [tex]2.416 \times 10^{-5}[/tex] m²/s.Prandtl number, Pr = 0.7241.Next, we would solve for the Rayleigh number to enable us determine the heat transfer coefficient by using the boundary layer equations:
[tex]R_{aL}=\frac{g\beta \Delta T l^3}{v\alpha } \\\\R_{aL}=\frac{9.8 \;\times \;\frac{1}{318} \;\times \;(75-15) \;\times \;0.15^3 }{1.750 \times 10^{-5}\; \times \;2.416 \times 10^{-5} } \\\\R_{aL}=\frac{9.8\; \times 0.00315 \;\times \;60\; \times\; 0.003375 }{4.228 \times 10^{-10} }\\\\R_{aL}=1.48 \times 10^{7}[/tex]
Also take note, g(Pr) is given by this equation:
[tex]g(P_r)=\frac{0.75P_r}{[0.609 \;+\;1.221\sqrt{P_r}\; +\;1.238P_r]^\frac{1}{4} } \\\\g(P_r)=\frac{0.75(0.7241)}{[0.609 \;+\;1.221\sqrt{0.7241}\; +\;1.238(0.7241)]^\frac{1}{4} }\\\\g(P_r)=\frac{0.543075}{[0.609 \;+\;1.221\sqrt{0.7241}\; +\;1.238(0.7241)]^\frac{1}{4} }\\\\g(P_r)=\frac{0.543075}{[2.5444]^\frac{1}{4} }\\\\g(P_r)=\frac{0.543075}{1.2630 }[/tex]
g(Pr) = 0.430
For GrL, we have:
[tex]G_{rL}=\frac{R_{aL}}{P_r} \\\\G_{rL}=\frac{1.48 \times 10^7}{0.7241} \\\\G_{rL}=1.99 \times 10^7[/tex]
Since the Rayleigh number is less than 10⁹, the flow is laminar and the condition is given by:
[tex]N_{uL}=\frac{h_{L}L}{k} = \frac{4}{3} (\frac{G_{rL}}{4} )^\frac{1}{4} g(P_r)\\\\h_{L}=\frac{0.02699}{0.15} \times [\frac{4}{3} \times (\frac{1.99 \times 10^7}{4} )^\frac{1}{4} ]\times 0.430\\\\h_{L}= 0.1799 \times 62.9705 \times 0.430\\\\h_{L}=4.87\;W/m^2k[/tex]
Based on empirical correlation method, the average heat transfer coefficient for the plate is given by this equation:
[tex]N_{uL}=\frac{h_{L}L}{k} =0.68 + \frac{0.670 R_{aL}^\frac{1}{4}}{[1+(\frac{0.492}{P_r})^\frac{9}{16}]^\frac{4}{19} } \\\\h_{L}=\frac{0.02699}{0.15} \times ( 0.68 + \frac{0.670 (1.48 \times 10^7)^\frac{1}{4}}{[1+(\frac{0.492}{0.7241})^\frac{9}{16}]^\frac{4}{19} })\\\\h_{L}=4.87\;W/m^2k[/tex]
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How frequently should vehicle registration be renewed?
Answer:
When the renewal period comes around (with respect to the license expiry date).
Explanation:
Select true/false for each of the following statements regarding copper & copper alloys:: (a) copper has a higher elastic modulus than aluminum. (b) the density of copper is closer to that of aluminum than it is to iron. (c) bronze is an alloy of copper and zinc. (d) copper and its alloys form a green tarnish over time, consisting of sulfides and carbonates. (e) copper is relatively resistant to corrosion by neutral and even mildly basic water, making it useful for freshwater plumbing applications.
A: Copper has a higher elastic modulus than aluminum.
TrueB: The density of copper is closer to that of aluminum than it is to iron.
FalseC: Bronze is an alloy of copper and zinc.
FalseD: Copper and its alloys form a green tarnish over time, consisting of sulfides and carbonates.
TrueE: Copper is relatively resistant to corrosion by neutral and even mildly basic water, making it useful for freshwater plumbing applications.
TrueAre there more pressing issues that we should be focusing on?(i.e. inflation and gas prices?)
Answer:
gas
Explanation:
As we speak gas is to high and is making it unconfortable for people to live normaly.
A piece of copper steel (specific heat = 490 kg K) has a mass of 300 g. If is heated to
150°C, then plunged into 4.00 kg water (specific heat = 4180 kg at 20°C, what will
be the final temperature at equilibrium?
The Given Data were properly outline and the relation for the quantity of heated at equilibrium was used to compute the temperature as 18.84°C
Heat CapacityGiven Data
Mass of Copper m1 = 300g = 0.3kgSpecific heat of copper c1 = 490Kg KInitial Temperature of Copper T1= 150°CMass of water m2 = 4kgSpecific heat of water = 42180 Kg KInitial Temperature of water T1= 20°CAt equilibrium, the final temperature of the system T2 will be same for both copper and water
McΔT(copper) = McΔT(water)
0.3*490*(T2 - 150) = 4*4180*(T2-20)
147*(T2 - 150) =16720*(T2-20)
147T2 - 22050 = 16720T2 - 334400
collect like terms
147T2 -16720T2 = - 334400+22050
147T2 -16720T2 = - 334400+22050
-16573T2 = -312350
16573T2 = 312350
Divide both sides by 16573
T2 = 312350/16573
T2 = 18.84°C
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Water is flowing steadily through a venturi that is oriented vertically. The venturi is attached to a mercury manometer that reads a 14. 3-inch deflection. 14. 3" z 30" 12" 6" a. ) 5 Points. In which direction is the water flowing? Justify your answer
Due to the fact that there is a 14.3inch deflection in the manometer, water is flowing towards the regions that have low pressure.
How does this water flow to low region areas?The fluid that is contained in the manometer is moving towards areas of low pressure. This means they are going to areas with high velocity.
The areas that have low cross sections would flow with a constant rate. This venturi would have low pressure because it has low cross sectional area.
The fluid in the device would then have to move from bottom to top towards the neck of the mercury.
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List three examples of waves that can transfer energy without going through a medium
Electromagnetic waves can transfer energy without a material medium.
3 examples of elctromagnetic energy include: Radio wave, X-rays and gamma rays
What is wave?A wave is a disturbance that transfers energy from one point to another.
Electromagnetic waves are waves that does not require a material medium for the tranfer of energy
Radio waveGamma raysX-raysLight waveRead more on Electromagnetic waves here: https://brainly.com/question/13874687
Many appliances come with___ratings, which mean that the
device or machine will run with fewer associated costs than previous
models.
Consider a homogeneous spherical piece of radioactive material of radius ro = 0.04 m that is generating heat at a constant rate of ėgen = 5 x 107 w/m3 . the heat generated is dissipated to the environment steadily. the outer surface of the sphere is maintained at a uniform temperature of 110°c and the thermal conductivity of the sphere is k = 15 w/m·k. assuming steady one-dimensional heat transfer, (a) express the differential equation and the boundary conditions for heat conduction through the sphere, (b) obtain a relation for the variation of temperature in the sphere by solving the differential equation, and (c) determine the temperature at the center of the sphere.
Answer:
Please report my answer
Explanation:
I want my account deleted
A traffic flow has density 61 veh/km when the speed is 59 veh/hr. If a flow has a jam density of 122 veh/km, what is the maximum flow in veh/hr (in whole number)? Use Greenshield Model.
Since this traffic flow has a jam density of 122 veh/km, the maximum flow is equal to 3,599 veh/hr.
Given the following data:
Density = 61 veh/km.Speed = 59 km/hr.Jam density = 122 veh/km.How to calculate the maximum flow.According to Greenshield Model, maximum flow is given by this formula:
[tex]q_{max}=\frac{V_f \times K_i}{4}[/tex]
Where:
[tex]V_f[/tex] is the free flow speed.[tex]K_i[/tex] is the Jam density.In order to calculate the free flow speed, we would use this formula:
[tex]V_f =2 V\\\\V_f =2\times 59\\\\V_f=118\;km/hr[/tex]
Substituting the parameters into the model, we have:
[tex]q_{max}=\frac{118 \times 122}{4}\\\\q_{max}=\frac{14396}{4}[/tex]
Max flow = 3,599 veh/hr.
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what is the purpose of placing a large electrolytic capacitor in the output side of a power supply
Answer:
When the AC power is larger than the DC load's needs, a big filter capacitor is typically employed to absorb and store energy, and to give energy to the load when the AC power is lower.
Explanation:
What should you do if you encounter a fishing boat while out in your vessel?.
Answer:
if you encounter fishing or hunting boats while you are paddling, be courteous.
Give them a wide berth.
Never run overfishing lines. Be aware that anglers may have lines out to the sides of their boat or trolling behind them.
Explanation:
Traveling a average speed at 55mph how many miles will you travel in9 hours
Which of the following would not be a good reason to use a linear model?
Thank
The disadvantage of using a linear model is that; It is sensitive to outliers and prone to multicollinearity.
What is the Linear Regression Model?Linear regression is defined as a regression technique whereby the independent variable has a linear relationship with the dependent variable.
Now, there are some advantages of this model in statistics such as;
Linear regression performs exceptionally well for linearly separable data.It is easy to implement and interpret.It carries out extrapolation beyond a specific data set.However, there are some disadvantages such as;
It is very sensitive to outliers.
It is prone to having multicollinearity.
It assumes linearity between dependent and independent variables.
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Time left 0:35:32 Three steel rod (E = 200 GPa) supports 36 KN Load P. Each of the rods AB and CD has a 200 mm? cross- sectional area and rod EF has 625 mm2 cross-sectional area. C D Compute for the stress in the rod. AB. a. 15.25 MPa b. 38.10 MPa C 19.05 MPa d. 30.50 MPa
Answer:
tama po ba
Explanation:
correct me if im wrong
Explain the difference between a geostationary and a polar orbit, as it relates to satellites
A geostationary orbit is in same direction as the spinning of the earth while polar orbit is along the poles
What is an orbit as used for satellites?Orbit describes the pathway a satellite moves. the pathway is usually circular.
Polar orbit refers to orbits that traces along the poles that is North pole and South pole. owing to the spherical nature of the earth polar orbits are shorter. This allows for a shorter time to complete a revolution.
Geostationary orbit as against the polar orbit , geostationary orbits traces same path as the Earth's spinning. This path os longer and will require more time to complete. Satellites tracing this orbits are launched further away about 36000 km above the earths surface while satellites on polar orbits is shorter about 200 km - 2000 km
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what would be the output signal
of two input binary signal given
by A - 100101 and B = 110110
are applied to:
a) OR-gate
b) NAND-gate and XOR gate
U lungul 200 m. If A = 100101 and B = 110110 are applied to X-NOR gate, then the output will be :- plo (1) 101100 (2)011011 (31110111 (4) 010011 As shown in ..
Most open-drive compressors use bolt-on
service valves, which cannot be replaced.
O True
O False
Most open-drive compressors use bolt-on service valves, which cannot be replaced is a false statement.
What is an Open Drive Compressor?Open Drive Compressor is a term that is often called a coupler drive. This is known to be a fully Serviceable motor that is said to drives the compressor through the use of a Coupling or Belt.
Most open-drive compressors use bolt-on service valves, which cannot be replaced is a false because open drive compressors are said to be driven by a motor.
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engineering economics
Explanation:
mathematics education grade 7
A strain gauge is used to measure the strain on a vibrating beam which can vibrate up to a maximum frequency of 60 Hz. The strain gauge analog signal is converted in to a digital signal via an Analog to Digital Converter (ADC) in order to store the data on a computer hard drive. The engineer responsible for this measurement mistakenly selects a sampling frequency of 90 Hz for the ADC. (a) Determine the alias frequency due to the small sampling frequency. (b) Propose a sampling frequency that will not result into aliasing of the analog signal (make sure to provide your rationale for selecting this frequency)
The aliased frequency that is due to small sampling frequency is 675 Hz.
The proposed sampling frequency is 2f = 120
How to solve for the aliased frequencyThe signal frequency that is given in the question is 60Hz
The sampling frequency is 90Hz
a. Using Nyquist frequency,
fn = 0.5*90Hz = 45Hz
The aliased frequency = |n*fn - fs|
aliased frequency = |n*fn - fs|
We have n >= 1/Fs = 17ms
Then the aliased frequency is = 17 x 45 - 90
= 675 Hz
b) The Nyquist sampling theoremIn order to avoid aliasing the sampling frequency, this has to be at least two times the highest frequency.
Therefore Fs =
2xF = 120Hz
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Q1. (20 marks) Entropy Analysis of the heat engine: consider a 35% efficient heat engine operating between a large, high- temperature reservoir at 1000 K (727 °C) and a large, cold reservoir at 308 K (35°C). If it withdraws 1.2 MJ/s from the high-temperature reservoir, what would be the rate of loss of entropy from that reservoir and what would be the rate of gain by the low-temperature reservoir? (4 marks) b. Express the work done by the engine in watts. (3 marks) What would be the total entropy gain of the system? d. Determine Carnot efficiency and recalculate the a, b, and c, accordingly.
With a high temperature of 1000k and a cold temperature of 308K, The rate of gain for the high reservoir would be 780 kj/s.
A. η = 35%
[tex]\frac{w}{Q1} = \frac{35}{100}[/tex]
W = [tex]1.2*\frac{35}{100}*1000kj/s[/tex]
W = 420 kj/s
Q2 = Q1-W
= 1200-420
= 780 kJ/S
What is the workdone by this engine?B. W = 420 kj/s
= 420x1000 w
= 4.2x10⁵W
The work done is 4.2x10⁵W
c. 780/308 - 1200/1000
= 2.532 - 1.2
= 1.332kj
The total enthropy gain is 1.332kj
D. Q1 = 1200
T1 = 1000
[tex]\frac{1200}{1000} =\frac{Q2}{308} \\\\Q2 = 369.6 KJ[/tex]
Cournot efficiency = W/Q1= 1200 - 369.6/1200
= 69.2 percent
change in s is zero for the reversible heat engine.
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what is the direct current generator
Answer:
A direct-current (DC) generator is a rotating machine that supplies an electrical output with unidirectional voltage and current.
Explanation:
Hope this helps
Kinetic energy kx is 1/2mvx2. evaluate the mean square kinetic energy < kx2 >in one dimension for n2 molecules at 25°c (hint: in the derivation of < kx2 > use f (vx.) )
The mean kinetic energy of the N₂ molecules at 25 °C is 3593.519 joules per mole.
How to estimate the mean square kinetic energy associated to gas molecules
Let suppose that the gas sample behaves ideally. The Graham's law establishes a connection between the ideal gas model and the kinetic theory of gases.
In this question we need to use this law to estimate the average kinetic energy (Kₐ), in joules per mole, of a diatomic gas (N₂), which is defined by the following expression:
[tex]K_{a} = \frac{3}{2}\cdot R_{u}\cdot T[/tex] (1)
Where:
[tex]R_{u}[/tex] - Ideal gas constant, in joules per mole-Kelvin.[tex]T[/tex] - Temperature, in KelvinIf we know that [tex]R_{u} = 8.314\,\frac{J}{mol\cdot K}[/tex] and [tex]T = 288.15\,K[/tex], then the average kinetic energy is:
[tex]K_{a} = \frac{3}{2}\cdot \left(8.314\,\frac{J}{mol\cdot K} \right) \cdot (288.15\,K)[/tex]
[tex]K_{a} = 3593.519\,\frac{J}{mol}[/tex]
The mean kinetic energy of the N₂ molecules at 25 °C is 3593.519 joules per mole. [tex]\blacksquare[/tex]
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What is the wavelength of a photon with an energy of 3. 38 x 10^-19 j
The photon has a wavelength of 588 nm
what is a wavelength?Wavelength is the distance between two points along the path of the wave.
it is usually represented by λ
Energy of a photon, E = ( h c ) / λ
where:
h is Planck's constant = 6.626 × 10 -34 Js
c is speed of light = 3.0 * 10^8 m/s
λ = ( h c ) / E
λ = ( ( 6.626 × 10 -34 ) * ( 3.0 * 10^8 ) ) / 3.38 * 10^-19
λ = 5.88 * 10^-7 m
λ = 588 * 10^-9 m = 588 nm
λ = 588 nm = 588 nanometers
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How does data mining help interactive marketing for a business?
By predicting which customers are lively to go to a competitor
By identifying which prospects should be included in a mailing list
By revealing the difference between a typical customer this month and last
By predicting what each individual accessing a website is most likely interested in seeing
The way in which data mining helps interactive marketing for a business firm is: D. By predicting what each individual accessing a website is most likely interested in seeing.
What is data mining?Data mining can be defined as a strategic process that typically involves extracting and analyzing data that are contained in large databases, especially through the use of specialized software to generate new information.
In this context, a business firm can adopt the use of data mining to enhance and facilitate interactive marketing by creating a process that can effectively and efficiently predict what each individual (customer) accessing their website is most likely interested in seeing.
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What was the role of the rotors in the enigma machine?.
Answer:
Implements a reordering of the letters of the alphabet.
Explanation: GIVE ME 5 STARS AND a HEART!!! Those contacts are wired across the rotor so that each contact on the left connects to the contact on the right in some scrambled arrangement. Each rotor, therefore, implements a reordering of the letters of the alphabet, which mathematicians call a permutation.
You may not operate a vehicle unless all child passengers __________ are securely fastened into an approved child restraint device.
Answer:
You may not operate a vehicle unless all child passengers under the age of 16 years are either wearing a safety belt assembly or are securely fastened into an approved child restraint device.
Explanation:
About what thickness of aluminum is needed to stop a beam of (a) 2.5-MeV electrons, (b) 2.5-MeV protons, and (c) 10-MeV alpha particles?
The thickness of aluminium needed to stop the beam electrons, protons and alpha particles at the given dfferent kinetic energies is 1.5 x 10⁻¹⁴ m.
Thickness of the aluminum
The thickness of the aluminum can be determined using from distance of closest approach of the particle.
[tex]K.E = \frac{2KZe^2}{r}[/tex]
where;
Z is the atomic number of aluminium = 13e is charge r is distance of closest approach = thickness of aluminiumk is Coulomb's constant = 9 x 10⁹ Nm²/C²For 2.5 MeV electrons[tex]r = \frac{2KZe^2}{K.E} \\\\r = \frac{2 \times 9\times 10^9 \times 13\times (1.6\times 10^{-19})^2}{2.5 \times 10^6 \times 1.6 \times 10^{-19}} \\\\r = 1.5 \times 10^{-14} \ m[/tex]
For 2.5 MeV protonsSince the magnitude of charge of electron and proton is the same, at equal kinetic energy, the thickness will be same. r = 1.5 x 10⁻¹⁴ m.
For 10 MeV alpha-particlesCharge of alpah particle = 2e
[tex]r = \frac{2KZe^2}{K.E} \\\\r = \frac{2 \times 9\times 10^9 \times 13\times (2 \times 1.6\times 10^{-19})^2}{10 \times 10^6 \times 1.6 \times 10^{-19}} \\\\r = 1.5 \times 10^{-14} \ m[/tex]
Thus, the thickness of aluminium needed to stop the beam electrons, protons and alpha particles at the given dfferent kinetic energies is 1.5 x 10⁻¹⁴ m.
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what is happening in the mechanical engineering field right now
Answer:
With the ongoing pandemic, businesses have shifted their operations to online platforms while people have been forced to resort to work-from-home lifestyles to prevent the further prevent the spread of the virus.
What's the difference between a scale and a scale drawing?
scale is used to make a scale drawing. every scale drawing has it's sclae written for proper interpreatation
What is a scale?
A Scale is the ratio of a sketched model and the actual measuremnts while a scale drawing is a sketched model that was carefully made such that every measurement in the sketch could be represented to the site or actual mearuement through the scale with very little or no error
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To make a scale drawing, scale is used. For correct interpretation, every scale drawing has its own scale inscribed on it.
What exactly is a scale?A scale drawing is a sketched model that has been meticulously prepared so that every measurement in the sketch may be conveyed to the site or actual measurement through the scale with very little or no mistake.
A weighing apparatus or equipment with two pans of equal weight hung from its ends —usually used in the plural, either pan or tray of a balance scale.
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