Answer:
the average normal stress in the bar is : [tex]\mathbf{\sigma = (32.5 - 20x )MPa}[/tex]
Explanation:
The free body flow of the missing diagram is attached to the answer below.
From the information given:
Let consider the sum of forces along horizontal direction to be equal to zero.
[tex]\begin{array}{l}\\\sum {{F_x}} = 0\\\\3 + 8\left( {1.25 - x} \right) - N = 0\\\\N = \left( {13 - 8x} \right){\rm{ kN}}\\\end{array}[/tex]
The average normal stress in the bar can be calculated by the formula:
[tex]\sigma = \dfrac{N}{A}[/tex]
where;
[tex]\sigma =[/tex] average normal stress in the bar
A = cross sectional area in the bar and it is given by: [tex]400*10^{-6 } m^2[/tex]
N = (13- 8x) kN
∴ [tex]\sigma = \dfrac{(13-8)x}{400*10^{-6} m^2}[/tex]
[tex]\sigma = (32.5 - 20x )*10^3 kPa[/tex]
[tex]\sigma = (32.5 - 20x )MPa[/tex]
Thus; the average normal stress in the bar is : [tex]\mathbf{\sigma = (32.5 - 20x )MPa}[/tex]
The average normal stress in the bar as a function of x is equal to 32.5 - 20x MPa.
Given the following data:
Cross-sectional area of bar = [tex]400 \times 10^{-6}\;m^2[/tex]Range of x = 0.5 m < x ≤ 1.25 m.Force A = 3 kN.Force B = 8(1.25-x) kN.To calculate the average normal stress in the bar as a function of x.
How to calculate average normal stress.First of all, we would determine the sum of the forces acting on the bar in the horizontal direction;
[tex]\sum F_x=0\\\\3+8(1.25-x)-N=0\\\\3+10-8x-N=0\\\\13-8x-N=0\\\\N=(13-8x)\; kN[/tex]
For the average normal stress:
Mathematically, the average normal stress is given by this formula:
[tex]\sigma = \frac{N}{A}[/tex]
Where:
A is the cross-sectional area.N is the resultant force.Substituting the parameters into the formula, we have;
[tex]\sigma = \frac{(13-8x) \times 10^3}{400 \times 10^{-6}}\\\\\sigma = \frac{(13-8x) \times 10^{3+6}}{400}\\\\\sigma =(32.5-20x) \times 10^{9}[/tex]
Note: 1 MPa = [tex]1\times 10^9\;Pa[/tex]
Average normal stress = 32.5 - 20x MPa.
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Consider a steady developing laminar flow of water in a constant-diameter horizontal discharge pipe attached to a tank. The fluid enters the pipe with nearly uniform velocity V and pressure P1. The velocity profile becomes parabolic after a certain distance with a momentum correction factor of 2 while the pressure drops to P2. Identify the correct relation for the horizontal force acting on the bolts that hold the pipe attached to the tank.
Answer:
hello attached is the free body diagram of the missing figure
Fr = [tex]\frac{\pi }{4} D^2 [ ( P1 - P2) - pV^2 ][/tex]
Explanation:
Average velocity is constant i.e V1 = V2 = V
The momentum equation for the flow in the Z - direction can be expressed as
-Fr + P1 Ac - P2 Ac = mB2V2 - mB1V1 ------- equation 1
Fr = horizontal force on the bolts
P1 = pressure of fluid at entrance
V1 = velocity of fluid at entrance
Ac = cross section area of the pipe
P2 and V2 = pressure and velocity of fluid at some distance
m = mass flow rate of fluid
B1 = momentum flux at entrance , B2 = momentum flux correction factor
Note; average velocity is constant hence substitute V for V1 and V2
equation 1 becomes
Fr = ( P1 - P2 ) Ac + mV ( 1 - 2 )
Fr = ( P1 - P2 ) Ac - mV ---------------- equation 2
equation for mass flow rate
m = pAcV
p = density of the fluid
insert this into equation 2 EQUATION 2 BECOMES
Fr = ( P1 - P2) Ac - pAcV^2
= Ac [ (P1 - P2) - pV^2 ] ---------- equation 3
Note Ac = [tex]\frac{\pi }{4} D^2[/tex]
Equation 3 becomes
Fr = [tex]\frac{\pi }{4} D^2[/tex] [ (P1 -P2 ) - pV^2 ] ------- relation for the horizontal force acting on the bolts
The design of a machine element calls for a 40-mm-outer-diameter shaft to transmit 46 kW. If the speed of rotation is 760 rpm, determine (a) the maximum shear stress in shaft (a). (b) the maximum shear stress in shaft (b) with inner diameter 25 mm.
Answer:
54.52 MPa
Explanation:
power P = 46 kW = 46000 W
speed N = 760 rpm
outer diameter of shaft D = 40 mm = 0.04 m
inner diameter of shaft d = 25 mm = 0.025 m
torque T = P/Ω
where Ω = angular speed in rad/s
Ω = 2πN/60 = (2 x 3.142 x 760)/60
Ω = 79.59 rad/s
from this,
torque T = 46000/79.59 = 577.96 N-m
the relationship between torque T, maximum shear stress τmax, and shaft diameters D and d is stated as
T = (π / 16) τmax ([tex]D^{4}[/tex] - [tex]d^{4}[/tex])/D
imputing the values, we have
577.96 = (3.142/16) x τmax x ([tex]0.04^{4}[/tex] - [tex]0.025^{4}[/tex])/0.04
577.96 = 0.196 x τmax x (5.4 x [tex]10^{-5}[/tex])
577.96 = 1.06 x [tex]10^{-5}[/tex] x τmax
τmax ≅ 54.52 MPa
Due to loading, a line segment has length 2 m with constant normal strain 0.25. What is the original length of the line segment? Due to loading, a line segment has length 2 with constant normal strain 0.25. What is the original length of the line segment? 1.60 m 1.50 m 1.75 m 2.67 m 2.50 m 2.25 m
Answer: A
Original length = 1.60 m
Explanation: given that due to loading, a line segment has length 2 with constant normal strain 0.25
Strain is the ratio of extension to original length. That is,
Strain = e/L
If a line segment has length 2, that means:
e + L = 2
e = 2 - L
And given that the strain = 0.25
Substitute all the parameters into the formula
0.25 = ( 2 - L ) / L
Cross multiply
0.25L = 2 - L
Collect the like terms
0.25L + L = 2
1.25L = 2
L = 2/ 1.25
L = 1.6 m
Therefore, original length is 1.6 metres
Calculate the Reynolds numbers for the flow of water through a nozzle with a radius of 0.250 cm and a garden hose with a radius of 0.900 cm, when the nozzle is attached to the hose. The flow rate through hose and nozzle is 0.500 L/s. Can the flow in either possibly be laminar
Answer:
In both cases, reynolds number is greater than 2000,so the flows can't be laminar.
Explanation:
A) For flow in a tube of uniform diameter, the reynolds number is defined as;
Re = 2ρvr/η
where;
ρ is the fluid density,
v its speed,
η is viscosity
r is the tube radius.
In this question,
We are given;
r = 0.25cm = 0.25 × 10^(-2) m
η of water has a standard value of 1.005 × 10^(-3)
ρ of water has a standard value of 1000 kg/m³
In the reynolds equation, we don't know the velocity. So let's calculate it from;
Q' = vA
Where; Q' is flow rate = 0.5 L/s = 0.0005 m³/s
Area = πr² = π × (0.25 × 10^(-2))²
Area = 1.963 × 10^(-5) m²
So, v = Q/A = 0.0005/(1.963 × 10^(-5)) = 25.5 m/s
So, Re = 2ρvr/η = (2*1000*25.5*0.25 × 10^(-2))/(1.005 × 10^(-3))
Re = 126865.67
Re > 2000 and so the flow is not laminar
B) Now,
radius = 0.9cm = 0.9 × 10^(-2) m
So, A = πr² = π × (0.9 × 10^(-2))²
A = 2.5447 × 10^(-4) m²
v = Q/A = 0.0005/(2.5447 × 10^(-4))
v = 1.965 m/s
Re = 2ρvr/η = (2*1000*1.965*0.9 × 10^(-2))/(1.005 × 10^(-3))
Re = 35194.03
Re > 2000. So flow is not laminar.
Q: Draw shear and bending moment diagram for the beam shown in
the figure. EI= constant
Answer:
Explanation:
Please
A 2.75-kN tensile load is applied to a test coupon made from 1.6-mm flat steel plate (E = 200 GPa, ν = 0.30). Determine the resulting change in (a) the 50-mm gage length, (b) the width of portion AB of the test coupon, (c) the thickness of portion AB, (d) the cross- sectional area of portion AB.
Answer:
I have attached the diagram for this question below. Consult it for better understanding.
Find the cross sectional area AB:
A = (1.6mm)(12mm) = 19.2 mm² = 19.2 × 10⁻⁶m
Forces is given by:
F = 2.75 × 10³ N
Horizontal Stress can be found by:
σ (x) = F/A
σ (x) = 2.75 × 10³ / 19.2 × 10⁻⁶m
σ (x) = 143.23 × 10⁶ Pa
Horizontal Strain can be found by:
ε (x) = σ (x)/ E
ε (x) = 143.23 × 10⁶ / 200 × 10⁹
ε (x) = 716.15 × 10⁻⁶
Find Vertical Strain:
ε (y) = -v · ε (y)
ε (y) = -(0.3)(716.15 × 10⁻⁶)
ε (y) = -214.84 × 10⁻⁶
PART (a)For L = 0.05m
Change (x) = L · ε (x)
Change (x) = 35.808 × 10⁻⁶m
PART (b)
For W = 0.012m
Change (y) = W · ε (y)
Change (y) = -2.5781 × 10⁻⁶m
PART(c)
For t= 0.0016m
Change (z) = t · ε (z)
where
ε (z) = ε (y) ,so
Change (z) = t · ε (y)
Change (z) = -343.74 × 10⁻⁹m
PART (d)
A = A(final) - A(initial)
A = -8.25 × 10⁻⁹m²
(Consult second picture given below for understanding how to calculate area)
The resulting change in the 50-mm gauge length; the width of portion AB of the test coupon; the thickness of portion AB; the cross- sectional area of portion AB are respectively; Δx = 35.808 × 10⁻⁶ m; Δy = -2.5781 × 10⁻⁶m; Δ_z = -343.74 × 10⁻⁹m; A = -8.25 × 10⁻⁹m²
What is the stress and strain in the plate?Let us first find the cross sectional area of AB from the image attached;
A = (1.6mm)(12mm) = 19.2 mm² = 19.2 × 10⁻⁶m
We are given;
Tensile Load; F = 2.75 kN = 2.75 × 10³ N
Horizontal Stress is calculated from the formula;
σₓ = F/A
σₓ = (2.75 × 10³)/(19.2 × 10⁻⁶)m
σₓ = 143.23 × 10⁶ Pa
Horizontal Strain is calculated from;
εₓ = σₓ/E
We are given E = 200 GPa = 200 × 10⁹ Pa
Thus;
εₓ = (143.23 × 10⁶)/(200 × 10⁹)
εₓ = 716.15 × 10⁻⁶
Formula for Vertical Strain is;
ε_y = -ν * εₓ
We are given ν = 0.30. Thus;
ε_y = -(0.3) * (716.15 × 10⁻⁶)
ε_y = -214.84 × 10⁻⁶
A) We are given;
Gauge Length; L = 0.05m
Change in gauge length is gotten from;
Δx = L * εₓ
Δx = 0.05 × 716.15 × 10⁻⁶
Δx = 35.808 × 10⁻⁶ m
B) From the attached diagram, the width is;
W = 0.012m
Change in width is;
Δy = W * ε_y
Δy = 0.012 * -214.84 × 10⁻⁶
Δy = -2.5781 × 10⁻⁶m
C) We are given;
Thickness of plate; t = 1.6 mm = 0.0016m
Change in thickness;
Δ_z = t * ε_z
where;
ε_z = ε_y
Thus;
Δ_z = t * ε_y
Δ_z = 0.0016 * -214.84 × 10⁻⁶
Δ_z = -343.74 × 10⁻⁹m
D) The change in cross sectional area is gotten from;
ΔA = A_final - A_initial
From calculating the areas, we have;
A = -8.25 × 10⁻⁹ m²
Read more about stress and strain in steel plates at; https://brainly.com/question/1591712
A horizontal turbine takes in steam with an enthalpy of h = 2.80 MJ/kg at 45 m/s. A steam-water mixture exits the turbine with an enthalpy of h = 1.55 MJ/kg at 20 m/s. If the heat loss to the surroundings from the turbine is 300 J/s, determine the power the fluid supplies to the turbine. The mass flow rate is 0.85 kg/s.
Answer:
The power that fluid supplies to the turbine is 1752.825 kilowatts.
Explanation:
A turbine is a device that works usually at steady state. Given that heat losses exists and changes in kinetic energy are not negligible, the following expression allows us to determine the power supplied by the fluid to the turbine by the First Law of Thermodynamics:
[tex]-\dot Q_{loss} - \dot W_{out} + \dot m \cdot \left[(h_{in}-h_{out}) + \frac{1}{2}\cdot (v_{in}^{2}-v_{out}^{2}) \right] = 0[/tex]
Output power is cleared:
[tex]\dot W_{out} = -\dot Q_{loss} + \dot m \cdot \left[(h_{in}-h_{out})+\frac{1}{2}\cdot (v_{in}^{2}-v_{out}^{2}) \right][/tex]
If [tex]\dot Q_{loss} = 0.3\,kW[/tex], [tex]\dot m = 0.85\,\frac{kg}{s}[/tex], [tex]h_{in} = 2800\,\frac{kJ}{kg}[/tex], [tex]h_{out} = 1550\,\frac{kJ}{kg}[/tex], [tex]v_{in} = 45\,\frac{m}{s}[/tex] and [tex]v_{out} = 20\,\frac{m}{s}[/tex], then:
[tex]\dot W_{out} = -0.3\,kW + \left(0.85\,\frac{kg}{s} \right)\cdot \left\{\left(2800\,\frac{kJ}{kg}-1550\,\frac{kJ}{kg} \right)+\frac{1}{2}\cdot \left[\left(45\,\frac{m}{s} \right)^{2}-\left(20\,\frac{m}{s} \right)^{2}\right] \right\}[/tex]
[tex]\dot W_{out} = 1752.825\,kW[/tex]
The power that fluid supplies to the turbine is 1752.825 kilowatts.
A tubular reactor has been sized to obtain 98% conversion and to process 0.03 m^3/s. The reaction is a first-order irreversible isomerization. The reactor is 3 m long, with a cross- sectional area of 25 dm^2. After being built, a pulse tracer test on the reactor gave the following data: tm = 10 s and σ2 = 65 s2. What conversion can be expected in the real reactor?
Answer:
The conversion in the real reactor is = 88%
Explanation:
conversion = 98% = 0.98
process rate = 0.03 m^3/s
length of reactor = 3 m
cross sectional area of reactor = 25 dm^2
pulse tracer test results on the reactor :
mean residence time ( tm) = 10 s and variance (∝2) = 65 s^2
note: space time (t) =
t = [tex]\frac{A*L}{Vo}[/tex] Vo = flow metric flow rate , L = length of reactor , A = cross sectional area of the reactor
therefore (t) = [tex]\frac{25*3*10^{-2} }{0.03}[/tex] = 25 s
since the reaction is in first order
X = 1 - [tex]e^{-kt}[/tex]
[tex]e^{-kt}[/tex] = 1 - X
kt = In [tex]\frac{1}{1-X}[/tex]
k = In [tex]\frac{1}{1-X}[/tex] / t
X = 98% = 0.98 (conversion in PFR ) insert the value into the above equation then
K = 0.156 [tex]s^{-1}[/tex]
Calculating Da for a closed vessel
; Da = tk
= 25 * 0.156 = 3.9
calculate Peclet number Per using this equation
0.65 = [tex]\frac{2}{Per} - \frac{2}{Per^2} ( 1 - e^{-per})[/tex]
therefore
[tex]\frac{2}{Per} - \frac{2}{Per^2} (1 - e^{-per}) - 0.65 = 0[/tex]
solving the Non-linear equation above( Per = 1.5 )
Attached is the Remaining part of the solution
for an electromotive force to be induced across a vertical loop from the field of an infinite length line of fixed current in the z axis the loop must be moving to?
Answer:
The correct answer to the following question will be "[tex]a_{x}[/tex] or [tex]a_{y}[/tex]".
Explanation:
Since along that same z-axis none electromagnetic field would be triggered as being in the same orientation loop movement of them across different line portions would allow some caused emf/voltage to be canceled. And the only logical choice seems to be either x or y-axes.The magnetic field of fluctuation should indeed be changed and changed across both X as well as Y directions.So that the above is the appropriate choice.
A specimen of a 4340 steel alloy with a plane strain fracture toughness of 54.8 MPa (50 ksi ) is exposed to a stress of 2023 MPa (293400 psi). Assume that the parameter Y has a value of 1.14. (a) If the largest surface crack is 0.2 mm (0.007874 in.) long, determine the critical stress .
Answer:
Explanation:
The formula for critical stress is
[tex]\sigma_c=\frac{K}{Y\sqrt{\pi a} }[/tex]
[tex]\sigma_c =\texttt{critical stress}[/tex]
K is the plane strain fracture toughness
Y is dimensionless parameters
We are to Determine the Critical stress
Now replacing the critical stress with 54.8
a with 0.2mm = 0.2 x 10⁻³
Y with 1
[tex]\sigma_c=\frac{54.8}{1\sqrt{\pi \times 0.2\times10^{-3}} } \\\\=\frac{54.8}{\sqrt{6.283\times10^{-4}} } \\\\=\frac{54.8}{0.025} \\\\=2186.20Mpa[/tex]
The fracture will not occur because this material can handle a stress of 2186.20Mpa before fracture. it is obvious that is greater than 2023Mpa
Therefore, the specimen does not failure for surface crack of 0.2mm
Q#1: Provide an example of a software project that would be amenable to the following models. Be specific. a. Waterfall b. Prototype c. Extreme Programming
Answer:
Waterfall model
Explanation:
The waterfall model is amenable to the projects. It focused on the data structure. The software architecture and detail about the procedure. It will interfere with the procedure. It interfaces with the characterization of the objects. The waterfall model is the first model that is introduced first. This model also called a linear sequential life cycle model.
The waterfall model is very easy to use. This is the earliest approach of the SDLC.
There are different phase of the waterfall:
Requirement analysisSystem DesignImplementationTestingDeploymentMaintenanceFor better thermal control it is common to make catalytic reactors that have many tubes packed with catalysts inside a larger shell (just like a shell and tube heat exchanger). Consider one tube inside such a reactor that is 2.5 m long with an inside diameter of 0.025 m. The catalyst is alumina spheres with a diameter of 0.003 m. The particle density is 1300 kg/m3 and the bed void fraction is 0.38. Compute the pressure drop seen for a superficial mass flux of 4684 kg/m2hr. The feed is methane at a pressure of 5 bar and 400 K. At these conditions the density of the gas is 0.15 mol/dm-3 and the viscosity is 1.429 x 10-5 Pa s.
Answer:
the pressure drop is 0.21159 atm
Explanation:
Given that:
length of the reactor L = 2.5 m
inside diameter of the reactor d= 0.025 m
diameter of alumina sphere [tex]dp[/tex]= 0.003 m
particle density = 1300 kg/m³
the bed void fraction [tex]\in =[/tex] 0.38
superficial mass flux m = 4684 kg/m²hr
The Feed is methane with pressure P = 5 bar and temperature T = 400 K
Density of the methane gas [tex]\rho[/tex] = 0.15 mol/dm ⁻³
viscosity of methane gas [tex]\mu[/tex] = 1.429 x 10⁻⁵ Pas
The objective is to determine the pressure drop.
Let first convert the Density of the methane gas from 0.15 mol/dm ⁻³ to kg/m³
SO; we have :
Density = 0.15 mol/dm ⁻³
Molar mass of methane gas (CH₄) = (12 + (1×4) ) = 16 mol
Density = [tex]0.1 5 *\dfrac{16}{0.1^3}[/tex]
Density = 2400
Density [tex]\rho_f[/tex] = 2.4 kg/m³
Density = mass /volume
Thus;
Volume = mass/density
Volume of the methane gas = 4684 kg/m²hr / 2.4 kg/m³
Volume of the methane gas = 1951.666 m/hr
To m/sec; we have :
Volume of the methane gas = 1951.666 * 1/3600 m/sec = 0.542130 m/sec
[tex]Re = \dfrac{dV \rho}{\mu}[/tex]
[tex]Re = \dfrac{0.025*0.5421430*2.4}{1.429*10^5}[/tex]
[tex]Re=2276.317705[/tex]
For Re > 1000
[tex]\dfrac{\Delta P}{L}=\dfrac{1.75 \rho_f(1- \in)v_o}{\phi_sdp \in^3}[/tex]
[tex]\dfrac{\Delta P}{2.5}=\dfrac{(1.75 *2.4)(1- 0.38)*0.542130}{1*0.003 (0.38)^3}[/tex]
[tex]\Delta P=8575.755212*2.5[/tex]
[tex]\Delta = 21439.38803 \ Pa[/tex]
To atm ; we have
[tex]\Delta P = \dfrac{21439.38803 }{101325}[/tex]
[tex]\Delta P =0.2115903087 \ atm[/tex]
ΔP ≅ 0.21159 atm
Thus; the pressure drop is 0.21159 atm
Eight switches are connected to PORTB and eight LEDs are connected to PORTA. We would like to monitor the first two least significant bits of PORTB (use masking technique). Whenever both of these bits are set, switch all LEDs of Port A on for one second. Assume that the name of the delay subroutine is DELAY. You do not need to write the code for the delay procedure.
Answer:
In this example, the delay procedure is given below in the explanation section
Explanation:
Solution
The delay procedure is given below:
LDS # $4000 // load initial memory
LDAA #$FF
STAA DDRA
LDAA #$00 //load address
STAA DDRB
THERE LDAA PORT B
ANDA #%00000011// port A and port B
CMPA #%0000011
BNE THERE
LDAA #$FF
STAA PORT A
JSR DELAY
LDAA #$00
STAA PORT A
BACK BRA BACK
Light acoustical panels in fire rated assemblies generally:
a. Compromise the fire rating by one hour.
b. Require hold down clips
c. Require pressure cleaning.
d. Are not allowed.
Answer:
a. Compromise the fire rating by one hour.
Explanation:
One hour fire rating is given to materials that can resist the fire exposure. The Acoustical panels controls reverberation and they are used for echo controls. The Fire rating is the passive fire protection which can resist standard fire. The test for fire rating also consider normal functioning of the material.
Time, budget, and safety are almost always considered to be
1. Efficiency
2. Constraints
3. Trade-offs
4. Criteria
Answer:
The answer is option # 2. (Constraints).
A piston-cylinder device initially at 0.45-m3 contains nitrogen gas at 600 kPa and 300 K. Now the gas is compressed isothermally to a volume of 0.2 m3. The work done on the gas during this compression process is _____ kJ.
Answer:
219kJ
Explanation:
The work done (W) on a gas in an isothermal process is given by;
W = -P₁V₁ ln[tex]\frac{V_{2}}{V_1}[/tex] -----------------(i)
Where;
P₁ = initial pressure of the gas
V₁ = initial volume of the gas
V₂ = final volume of the gas
From the question;
P₁ = 600kPa = 6 x 10⁵Pa
V₁ = 0.45m³
V₂ = 0.2m³
Substitute these values into equation (i) as follows;
W = -6 x 10⁵ x 0.45 x ln [tex]\frac{0.2}{0.45}[/tex]
W = -6 x 10⁵ x 0.45 x ln (0.444)
W = -6 x 10⁵ x 0.45 x -0.811
W = 2.19 x 10⁵
W = 219 x 10³
W = 219kJ
Therefore, the work done on the gas during the compression process is 219kJ
An Ideal gas is being heated in a circular duct as while flowing over an electric heater of 130 kW. The diameter of duct is 500 mm. The gas enters the heating section of the duct at 100 kPa and 27 deg C with a volume flow rate of 15 m3/s. If heat is lost from the gas in the duct to the surroundings at a rate of 80 kW, Calculate the exit temperature of the gas in deg C. (Assume constant pressure, ideal gas, negligible change in kinetic and potential energies and constant specific heat; Cp =1000 J/kg K; R = 500 J/kg K)
Answer:
Exit temperature = 32°C
Explanation:
We are given;
Initial Pressure;P1 = 100 KPa
Cp =1000 J/kg.K = 1 KJ/kg.k
R = 500 J/kg.K = 0.5 Kj/Kg.k
Initial temperature;T1 = 27°C = 273 + 27K = 300 K
volume flow rate;V' = 15 m³/s
W = 130 Kw
Q = 80 Kw
Using ideal gas equation,
PV' = m'RT
Where m' is mass flow rate.
Thus;making m' the subject, we have;
m' = PV'/RT
So at inlet,
m' = P1•V1'/(R•T1)
m' = (100 × 15)/(0.5 × 300)
m' = 10 kg/s
From steady flow energy equation, we know that;
m'•h1 + Q = m'h2 + W
Dividing through by m', we have;
h1 + Q/m' = h2 + W/m'
h = Cp•T
Thus,
Cp•T1 + Q/m' = Cp•T2 + W/m'
Plugging in the relevant values, we have;
(1*300) - (80/10) = (1*T2) - (130/10)
Q and M negative because heat is being lost.
300 - 8 + 13 = T2
T2 = 305 K = 305 - 273 °C = 32 °C
Consider a refrigerator that consumes 400 W of electric power when it is running. If the refrigerator runs only one-quarter of the time and the unit cost of electricity is $0.13/kWh, what is the electricity cost of this refrigerator per month (30 days)
Answer:
Electricity cost = $9.36
Explanation:
Given:
Electric power = 400 W = 0.4 KW
Unit cost of electricity = $0.13/kWh
Overall time = 1/4 (30 days) (24 hours) = 180 hours
Find:
Electricity cost
Computation:
Electricity cost = Electric power x Unit cost of electricity x Overall time
Electricity cost = 0.4 x $0.13 x 180
Electricity cost = $9.36
Given:
Electric power = 400 W = 0.4 KW
Over all Time = 30(1/4) = 7.5 days
Unit cost of electricity = $0.13/kWh
Find:
Electricity cost.
Computation:
Electricity cost = Electric power x Unit cost of electricity x Over all Time
Electricity cost = 0.4 x 0.13 x 7.5
Electricity cost = $
The benefit of using the generalized enthalpy departure chart prepared by using PR and TR as the parameters instead of P and T is that the single chart can be used for all gases instead of a single particular gas.
a. True
b. False
Engine oil (unused) flows at 1.81 x 10^-3 kg/s inside a 1-cm diameter tube that is heated electrically at a rate of 76 W/m. At a particular location where flow and heat transfer are fully developed, the wall temperature is 370K. Determine:
a. The oil mean temperature.
b. The centerline temperature.
c. The axial gradient of the mean temperature.
d. The heat transfer coefficient.
Answer:
(a)Tb = 330.12 K (b)Tc =304.73 K (c)19.81 K/m (d) h =60.65 W/m². K
Explanation:
Solution
Given that:
The mass flow rate of engine oil m = 1.81 x 10^-3 kg/s
Diameter of the tube, D = 1cm =0.01 m
Electrical heat rate, q =76 W/m
Wall Temperature, Ts = 370 K
Now,
From the properties table of engine oil we can deduce as follows:
thermal conductivity, k =0.139 W/m .K
Density, ρ = 854 kg/m³
Specific heat, cp = 2120 J/kg.K
(a) Thus
The wall heat flux is given as follows:
qs = q/πD
=76/π *0.01
= 2419.16 W/m²
Now
The oil mean temperature is given as follows:
Tb =Ts -11/24 (q.R/k) (R =D/2=0.01/2 = 0.005 m)
Tb =370 - 11/24 * (2419.16 * 0.005/0.139)
Tb = 330.12 K
(b) The center line temperature is given below:
Tc =Ts - 3/4 (qs.R/k)= 370 - 3/4 * ( 2419.16 * 0.005/0.139)
Tc =304.73 K
(c) The flow velocity is given as follows:
V = m/ρ (πR²)
Now,
The The axial gradient of the mean temperature is given below:
dTb/dx = 2 *qs/ρ *V*cp * R
=2 *qs/ρ*[m/ρ (πR²) *cp * R
=2 *qs/[m/(πR)*cp
dTb/dx = 2 * 2419.16/[1.81 x 10^-3/(π * 0.005)]* 2120
dTb/dx = 19.81 K/m
(d) The heat transfer coefficient is given below:
h =48/11 (k/D)
=48/11 (0.139/0.01)
h =60.65 W/m². K
An airplane flies from San Francisco to Washington DC at an air speed of 800 km/hr. Assume Washington is due east of San Francisco at a distance of 6000 km. Use a Cartesian system of coordinates centered at San Francisco with Washington in the positive x-direction. At cruising altitude, there is a cross wind blowing from north to south of 100 km/hr.
Required:
a. What must be the direction of flight for the plane to actually arrive in Washington?
b. What is the speed in the San Francisco to Washington direction?
c. How long does it take to cover this distance?
d. What is the time difference compared to no crosswind?
Answer:
A.) 7.13 degree north east
B.) 806.23 km/h
C.) 7.44 hours
D.) 0.06 hours
Explanation:
Assume Washington is due east of San Francisco and Francisco with Washington in the positive x-direction
Also, the cross wind is blowing from north to south of 100 km/hr in y coordinate direction.
A.) Using Cartesian system of coordinates, the direction of flight for the plane to actually arrive in Washington can be calculated by using the formula
Tan Ø = y/x
Substitute y = 100 km/h and x = 800km/h
Tan Ø = 100/800
Tan Ø = 0.125
Ø = Tan^-1(0. 125)
Ø = 7.13 degrees north east.
Therefore, the direction of flight for the plane to actually arrive in Washington is 7.13 degree north east
B.) The speed in the San Francisco to Washington direction can be achieved by using pythagorean theorem
Speed = sqrt ( 800^2 + 100^2)
Speed = sqrt (650000)
Speed = 806.23 km/h
C.) Let us use the speed formula
Speed = distance / time
Substitute the speed and distance into the formula
806.23 = 6000/ time
Make Time the subject of formula
Time = 6000/806.23
Time = 7.44 hours
D.) If there is no cross wind,
Time = 6000/800
Time = 7.5 hour
Time difference = 7.5 - 7.44
Time difference = 0.06 hours
Waste cooking oil is to be stored for processing by pouring it into tank A, which is connected by a manometer to tank B. The manometer is completely filled with water. Measurements indicate that the material of tank B will fail and the tank will burst if the air pressure in tank B exceeds 18 kPa. To what height h can waste oil be poured into tank A? If air is accidentally trapped in the manometer line, what will be the error in the calculation of the height?
KINDLY NOTE that there is a picture in the question. Check the picture below for the picture.
==================================
Answer:
(1). 1.2 metres.
(2). There is going to be the same pressure.
Explanation:
From the question above we can take hold of the statement Below because it is going to assist or help us in solving this particular Question or problem;
" Measurements indicate that the material of tank B will fail and the tank will burst if the air pressure in tank B exceeds 18 kPa."
=> Also, the density of oil = 930
That is if Pressure, P in B > 18kpa there will surely be a burst.
The height, h the can waste oil be poured into tank A is;
The maximum pressure = height × acceleration due to gravity × density) + ( acceleration due to gravity × density × height, j).
18 × 10^3 = (height, h × 10 × 930) + 10 × (2 - 1.25) × 1000.
When we make height, h the Subject of the formula then;
Approximately, Height, h = 1.2 metres.
(2). If air is accidentally trapped in the manometer line, what will be the error in the calculation of the height we will have the same pressure.
A nozzle receives an ideal gas flow with a velocity of 25 m/s, and the exit at 100 kPa, 300 K velocity is 250 m/s. Determine the inlet temperature if the gas is argon, helium, or nitrogen.
Given Information:
Inlet velocity = Vin = 25 m/s
Exit velocity = Vout = 250 m/s
Exit Temperature = Tout = 300K
Exit Pressure = Pout = 100 kPa
Required Information:
Inlet Temperature of argon = ?
Inlet Temperature of helium = ?
Inlet Temperature of nitrogen = ?
Answer:
Inlet Temperature of argon = 360K
Inlet Temperature of helium = 306K
Inlet Temperature of nitrogen = 330K
Explanation:
Recall that the energy equation is given by
[tex]$ C_p(T_{in} - T_{out}) = \frac{1}{2} \times (V_{out}^2 - V_{in}^2) $[/tex]
Where Cp is the specific heat constant of the gas.
Re-arranging the equation for inlet temperature
[tex]$ T_{in} = \frac{1}{2} \times \frac{(V_{out}^2 - V_{in}^2)}{C_p} + T_{out}$[/tex]
For Argon Gas:
The specific heat constant of argon is given by (from ideal gas properties table)
[tex]C_p = 520 \:\: J/kg.K[/tex]
So, the inlet temperature of argon is
[tex]$ T_{in} = \frac{1}{2} \times \frac{(250^2 - 25^2)}{520} + 300$[/tex]
[tex]$ T_{in} = \frac{1}{2} \times 119 + 300$[/tex]
[tex]$ T_{in} = 360K $[/tex]
For Helium Gas:
The specific heat constant of helium is given by (from ideal gas properties table)
[tex]C_p = 5193 \:\: J/kg.K[/tex]
So, the inlet temperature of helium is
[tex]$ T_{in} = \frac{1}{2} \times \frac{(250^2 - 25^2)}{5193} + 300$[/tex]
[tex]$ T_{in} = \frac{1}{2} \times 12 + 300$[/tex]
[tex]$ T_{in} = 306K $[/tex]
For Nitrogen Gas:
The specific heat constant of nitrogen is given by (from ideal gas properties table)
[tex]C_p = 1039 \:\: J/kg.K[/tex]
So, the inlet temperature of nitrogen is
[tex]$ T_{in} = \frac{1}{2} \times \frac{(250^2 - 25^2)}{1039} + 300$[/tex]
[tex]$ T_{in} = \frac{1}{2} \times 60 + 300$[/tex]
[tex]$ T_{in} = 330K $[/tex]
Note: Answers are rounded to the nearest whole numbers.
Which of the following is normally included in the criteria of a design?
1. Materials
2. Time
3. Budget
4. Efficiency
Answer:
i took the test and its budget
Explanation:
Budget, of the following is normally included in the criteria of a design. Thus, option (c) is correct.
What is design?The term design refers to the visual representation of image and shapes. The image is based on vector raster and bitmap. Who design the graphic is called graphic designer. The design main purpose to design of logo, word art, and advertisement design. The design mostly software as Coral Draw, Photoshop, Canva etc.
The criteria of a design are the budget. The budget was the financial as well as the monetary terminology. The criteria of the budget are the decided to how much they spend, and they save. The design on the country budget and the five-year plan.
As a result, the budget following is normally included in the criteria of a design. Therefore, option (c) is correct.
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Cathy works in a welding shop. While working one day, a pipe falls from scaffolding above and lands on her head, injuring her. Cathy complains to OSHA, but the company argues that because it has a "watch out for falling pipe" sign in the workplace that it gave fair warning. It also says that if Cathy wasn’t wearing a hardhat that she is responsible for her own injury. Which of the following is true?1. Common law rules could hold Cathy responsible for her own injury.2. Cathy’s employer may not be held liable for her injury if it fulfilled compliance and general duty requirements.3. OSHA rules can hold Cathy’s employer responsible for not maintaining a hazard-free workplace.4. More than one answer is correct.
Answer:1 common law
Explanation:
It also says that if Cathy wasn’t wearing a hardhat hat she is responsible for her own injury, more than one answer is correct.
What are OSHA rules?In this case, if Cathy's employer completes compliance and general duty requirements then the organization may not be held liable and again, the law can generally hold Cathy responsible for the injuries as she was not wearing the proper kits for such work.
According to OSHA, Cathy’s employer may not be held liable for her injury if it fulfilled compliance and general duty requirements.
You are entitled to a secure workplace. To stop workers from being murdered or suffering other types of harm at work, the Occupational Safety and Health Act of 1970 (OSH Act) was passed. According to the legislation, companies are required to give their workers safe working environments.
Therefore, more than one answer is correct.
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To determine the viscosity of a liquid of specific gravity 0.95, you fill to a depth of 12 cm a large container that drains through a 30 cm long vertical tube attached to the bottom. The tube diameter is 2 mm, and the rate of draining is found to be 1.9 cm3 /s. What is the fluid viscosity (assume laminar flow)
Answer:
Fluid viscosity, [tex]\mu = 2.57 * 10^{-3} kgm^{-1}s^{-1}[/tex]
Explanation:
Container depth, D = 12 cm = 0.12 m
Tube length, l = 30 cm = 0.3 m
Specific Gravity, [tex]\rho[/tex] = 0.95
Tube diameter, d = 2 mm = 0.002 m
Rate of flow, Q = 1.9 cm³/s = 1.9 * 10⁻⁶ m³/s
Calculate the velocity at point 2 ( check the diagram attached)
Rate of flow at section 2, [tex]Q = A_2 v_2[/tex]
[tex]Area, A_2 = \pi d^{2} /4\\A_2 = \pi/4 * 0.002^2\\A_2 = 3.14159 * 10^{-6} m^2[/tex]
[tex]v_{2} = Q/A_{2} \\v_{2} =\frac{1.9 * 10^{-6}}{3.14 * 10^{-6}} \\v_{2} = 0.605 m/s[/tex]
Applying the Bernoulli (energy flow) equation between Point 1 and point 2 to calculate the head loss:
[tex]\frac{p_{1} }{\rho g} + \frac{v_{1}^2 }{2 g} + z_1 = \frac{p_{2} }{\rho g} + \frac{v_{2}^2 }{2 g} + z_2 + h_f\\ z_1 = L + l = 0.12 + 0.3\\z_1 = 0.42\\p_1 = p_{atm}\\v_1 = 0\\z_2 = 0\\\frac{p_{atm} }{\rho g} + \frac{0^2 }{2 g} + 0.42= \frac{p_{atm} }{\rho g} + \frac{0.605^2 }{2 *9.8} +0 + h_f\\h_f = 0.401 m[/tex]
For laminar flow, the head loss is given by the formula:
[tex]h_f = \frac{128 Q \mu l}{\pi \rho g d^4} \\\\0.401 = \frac{128 * 1.9 * 10^{-6} * 0.3 \mu}{\pi *0.95* 9.8* 0.002^4}\\\\\\\mu = \frac{0.401 * \pi *0.95* 9.8* 0.002^4}{128 * 1.9 * 10^{-6} * 0.3} \\\\\mu = 2.57 * 10^{-3} kgm^{-1}s^{-1}[/tex]
Answer:
0.00257 kg / m.s
Explanation:
Given:-
- The specific gravity of a liquid, S.G = 0.95
- The depth of fluid in free container, h = 12 cm
- The length of the vertical tube , L = 30 cm
- The diameter of the tube, D = 2 mm
- The flow-rate of the fluid out of the tube into atmosphere, Q = 1.9 cm^3 / s
Find:-
To determine the viscosity of a liquid
Solution:-
- We will consider the exit point of the fluid through the vertical tube of length ( L ), where the flow rate is measured to be Q = 1.9 cm^3 / s
- The exit velocity ( V2 ) is determined from the relation between flow rate ( Q ) and the velocity at that point.
[tex]Q = A*V_2[/tex]
Where,
A: The cross sectional area of the tube
- The cross sectional area of the tube ( A ) is expressed as:
[tex]A = \pi \frac{D^2}{4} \\\\A = \pi \frac{0.002^2}{4} \\\\A = 3.14159 * 10^-^6 m^2[/tex]
- The velocity at the exit can be determined from the flow rate equation:
[tex]V_2 = \frac{Q}{A} \\\\V_2 = \frac{1.9*10^-^6}{3.14159*10^-^6} \\\\V_2 = 0.605 \frac{m}{s}[/tex]
- We will apply the energy balance ( head ) between the points of top-surface ( free surface ) and the exit of the vertical tube.
[tex]\frac{P_1}{p*g} + \frac{V^2_1}{2*g} + z_t_o_p = \frac{P_2}{p*g} + \frac{V^2_2}{2*g} + z_d_a_t_u_m + h_L[/tex]
- The free surface conditions apply at atmospheric pressure and still ( V1 = 0 ). Similarly, the exit of the fluid is also to atmospheric pressure. Where, z_top is the total change in elevation from free surface to exit of vertical tube.
- The major head losses in a circular pipe are accounted using Poiessel Law:
[tex]h_L = \frac{32*u*L*V}{S.G*p*g*D^2}[/tex]
Where,
μ: The dynamic viscosity of fluid
L: the length of tube
V: the average velocity of fluid in tube
ρ: The density of water
- The average velocity of the fluid in the tube remains the same as the exit velocity ( V2 ) because the cross sectional area ( A ) of the tube remains constant throughout the tube. Hence, the velocity also remains constant.
- The energy balance becomes:
[tex]h + L = \frac{V_2^2}{2*g} + \frac{32*u*L*V_2}{S.G*p*g*D^2} \\\\0.42 = \frac{0.605^2}{2*9.81} + \frac{32*u*(0.3)*(0.605)}{0.95*998*9.81*0.002^2} \\\\u = 0.00257 \frac{kg}{m.s}[/tex]
- Lets check the validity of the Laminar Flow assumption to calculate the major losses:
[tex]Re = \frac{S.G*p*V_2*D}{u} \\\\Re = \frac{0.95*998*0.605*0.002}{0.00257} \\\\Re = 446 < 2100[/tex]( Laminar Flow )
You want to plate a steel part having a surface area of 160 with a 0.002--thick layer of lead. The atomic mass of lead is 207.19 . The density of lead is 11.36 . How many atoms of lead are required
Answer:
To answer this question we assumed that the area units and the thickness units are given in inches.
The number of atoms of lead required is 1.73x10²³.
Explanation:
To find the number of atoms of lead we need to find first the volume of the plate:
[tex] V = A*t [/tex]
Where:
A: is the surface area = 160
t: is the thickness = 0.002
Assuming that the units given above are in inches we proceed to calculate the volume:
[tex]V = A*t = 160 in^{2}*0.002 in = 0.32 in^{3}*(\frac{2.54 cm}{1 in})^{3} = 5.24 cm^{3}[/tex]
Now, using the density we can find the mass:
[tex] m = d*V = 11.36 g/cm^{3}*5.24 cm^{3} = 59.5 g [/tex]
Finally, with the Avogadros number ([tex]N_{A}[/tex]) and with the atomic mass (A) we can find the number of atoms (N):
[tex] N = \frac{m*N_{A}}{A} = \frac{59.5 g*6.022 \cdot 10^{23} atoms/mol}{207.19 g/mol} = 1.73 \cdot 10^{23} atoms [/tex]
Hence, the number of atoms of lead required is 1.73x10²³.
I hope it helps you!
A very large thin plate is centered in a gap of width 0.06 m with a different oils of unknown viscosities above and below; one viscosity is twice the other. When the plate is pulled at a velocity of 0.3 m/s, the resulting force on one square meter of plate due to the viscous shear on both sides is 29 N. Assuming viscous flow and neglecting all end effects calculate the viscosities of the oils.
Answer:
The viscosities of the oils are 0.967 Pa.s and 1.933 Pa.s
Explanation:
Assuming the two oils are Newtonian fluids.
From Newton's law of viscosity for Newtonian fluids, we know that the shear stress is proportional to the velocity gradient with the viscosity serving as the constant of proportionality.
τ = μ (∂v/∂y)
There are oils above and below the plate, so we can write this expression for the both cases.
τ₁ = μ₁ (∂v/∂y)
τ₂ = μ₂ (∂v/∂y)
dv = 0.3 m/s
dy = (0.06/2) = 0.03 m (the plate is centered in a gap of width 0.06 m)
τ₁ = μ₁ (0.3/0.03) = 10μ₁
τ₂ = μ₂ (0.3/0.03) = 10μ₂
But the shear stress on the plate is given as 29 N per square meter.
τ = 29 N/m²
But this stress is a sum of stress due to both shear stress above and below the plate
τ = τ₁ + τ₂ = 10μ₁ + 10μ₂ = 29
But it is also given that one viscosity is twice the other
μ₁ = 2μ₂
10μ₁ + 10μ₂ = 29
10(2μ₂) + 10μ₂ = 29
30μ₂ = 29
μ₂ = (29/30) = 0.967 Pa.s
μ₁ = 2μ₂ = 2 × 0.967 = 1.933 Pa.s
Hope this Helps!!!
If the 1550-lb boom AB, the 190-lb cage BCD, and the 169-lb man have centers of gravity located at points G1, G2 and G3, respectively, determine the resultant moment produced by all the weights about point A.
Answer:
hello the required diagram is missing attached to the answer is the required diagram
7.9954 kip.ft
Explanation:
AB = 1550-Ib ( weight acting on AB )
BCD = 190 - Ib ( weight of cage )
169-Ib = weight of man inside cage
Attached is the free hand diagram of the question
calculate distance [tex]x![/tex]
= cos 75⁰ = [tex]\frac{x^!}{10ft}[/tex]
[tex]x! = 10 * cos 75^{o}[/tex] = 2.59 ft
calculate distance x
= cos 75⁰ = [tex]\frac{x}{30ft}[/tex]
x = 30 * cos 75⁰ = 7.765 ft
The resultant moment produced by all the weights about point A
∑ Ma = 0
Ma = 1550 * [tex]x![/tex] + 190 ( x + 2.5 ) + 169 ( x + 2.5 + 1.75 )
Ma = 1550 * 2.59 + 190 ( 7.765 + 2.5 ) + 169 ( 7.765 + 2.5 + 1.75 )
= 4014.5 + 1950.35 + 2030.535
= 7995.385 ft. Ib ≈ 7.9954 kip.ft
An 60-m long wire of 5-mm diameter is made of steel with E = 200 GPa and ultimate tensile strength of 400 MPa. If a factor of safety of 3.2 is desired, determine (a) the allowable tension in the wire (b) the corresponding elongation of the wire
Answer:
a) 2.45 KN
b) 0.0375 m
Explanation:
[tex](a) \quad \sigma_{v}=400 \times 10^{6} \mathrm{Pa} \quad A=\frac{\pi}{4} d^{2}=\frac{\pi}{4}(5)^{2}=19.635 \mathrm{mm}^{2}=19.635 \times 10^{-6} \mathrm{m}^{2}[/tex]
[tex]P_{U}=\sigma_{U} A=\left(400 \times 10^{6}\right)\left(19.635 \times 10^{-6}\right)=7854 \mathrm{N}[/tex]
[tex]P_{\text {al }}=\frac{P_{U}}{F S}=\frac{7854}{3.2}=2454 \mathrm{N}[/tex]
(b) [tex]\quad \delta=\frac{P L}{A E}=\frac{(2454)(60)}{\left(19.635 \times 10^{-6}\right)\left(200 \times 10^{9}\right)}=37.5 \times 10^{-3} \mathrm{m}[/tex]