Answer:
mama mia
Explanation:
haha
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.
For 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
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
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
a. Derive linear density expressions for BCC [110] and [111] directions in terms of the atomic radius R.
b. Compute and compare linear density values for these same two directions for iron (Fe).
A) The linear density expressions for BCC [110] and [111] directions in terms of the atomic radius R are;
i) LD_110 = √3/(4R√2)
ii) LD_111 = 1/(2R)
B) The linear density values for these same two directions for iron (Fe) are;
i) LD_110 = 2.4 × 10^(9) m^(-1)
ii) LD_111 = 4 × 10^(9) m^(-1)
Calculating Linear Density of Crystalline StructuresA) i) To find linear density expression for BCC 110, first of all we will calculate the length of the vector using the length of the unit cell which is 4R/√3 and the cell edge length which is 4R. Thus, the vector length can now be calculated from this expression;
√((4R)² - (4R/√3)²)
This reduces to; 4R√(1 - 1/3) = 4R√(2/3)
Now, the expression for the linear density of this direction is;
LD_110 =
Number of atoms centered on (110) direction/vector length of 110 direction
In this case, there is only one atom centered on the 110 direction. Thus;
LD_110 = 1/(4R√(2/3))
LD_110 = √3/(4R√2)
ii) The length of the vector for the direction 111 is equal to 4R, since
all of the atoms whose centers the vector passes through touch one another. In addition, the vector passes through an equivalent of 2 complete atoms. Thus, the linear density is;
LD_111 = 2/(4R) = 1/(2R)
B)i) From tables, the atomic radius for iron is 0.124 nm or 0.124 x 10^(-9) m. Therefore, the linear density for the [110] direction is;
LD_110 = √3/(4R√2) = √3/(4*0.124*10^(-9)(√2))
LD_110 = 2.4 × 10^(9) m^(-1)
ii) for the 111 direction, we have;
LD_111 = 1/(2R) = 1/(2*0.124*10^(-9))
LD_111 = 4 × 10^(9) m^(-1)
Read more about Linear Density of Crystalline Structures at; https://brainly.com/question/14831455
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
A well-insulated, rigid tank has a volume of 1 m3and is initially evacuated. A valve is opened,and the surrounding air enters at 1 bar, 27 °C. Heat is transferredto the tank by an electric resister at a constant rate for 5 minutes. After heating, the tank pressure is 1 bar and the temperature is 477 °C. Air can be modeled as an ideal gas. Find the power input required, in kW
Answer:
0.5 kW
Explanation:
The given parameters are;
Volume of tank = 1 m³
Pressure of air entering tank = 1 bar
Temperature of air = 27°C = 300.15 K
Temperature after heating = 477 °C = 750.15 K
V₂ = 1 m³
P₁V₁/T₁ = P₂V₂/T₂
P₁ = P₂
V₁ = T₁×V₂/T₂ = 300.15 * 1 /750.15 = 0.4 m³
[tex]dQ = m \times c_p \times (T_2 -T_1)[/tex]
For ideal gas, [tex]c_p[/tex] = 5/2×R = 5/2*0.287 = 0.7175 kJ
PV = NKT
N = PV/(KT) = 100000×1/(750.15×1.38×10⁻²³)
N = 9.66×10²⁴
Number of moles of air = 9.66×10²⁴/(6.02×10²³) = 16.05 moles
The average mass of one mole of air = 28.8 g
Therefore, the total mass = 28.8*16.05 = 462.135 g = 0.46 kg
∴ dQ = 0.46*0.7175*(750.15 - 300.15) = 149.211 kJ
The power input required = The rate of heat transfer = 149.211/(60*5)
The power input required = 0.49737 kW ≈ 0.5 kW.
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.
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]
A single crystal of a metal that has the FCC crystal structure is oriented such that a tensile stress is applied parallel to the [100] direction. If the critical resolved shear stress for this material is 1.98 MPa, calculate the magnitude of applied stress necessary to cause slip to occur on the (111) plane in the direction.
Answer:
the magnitude of the stress necessary to cause slip to occur on the (111) plane in the [tex][1 0 \overline 1][/tex] direction is 4.85 MPa
Explanation:
From the given information;
To determine the angle [tex]\phi[/tex] between the direction [100] and [111]; we have:
[tex]\phi = cos ^{-1} [\dfrac{u_1u_2+v_1v_2+w_1w_2}{ \sqrt{(u_1^2+v_1^2+w_1^2) (u_2^2+v_2^2+w_2^2) }}}[/tex]
where;
[u₁,v₁,w₁] and [u₂, v₂, w₂] are directional indices.
replacing 1 for u₁ , 0 for v₁ and 0 for w₁ ;
also replacing 1 for u₂, 1 for v₂ and 1 for w₂ ; we have :
[tex]\phi = cos ^{-1} [\dfrac{1*1+0*1+0*1}{ \sqrt{(1^2+0^2+0^2) (1^2+1^2+1^2) }}}[/tex]
[tex]\phi = 54.7^0[/tex]
To determine the angle [tex]\lambda[/tex] for the slip direction [tex][1 0 \overline 1][/tex]
[tex]\lambda= cos ^{-1} [\dfrac{u_1u_2+v_1v_2+w_1w_2}{ \sqrt{(u_1^2+v_1^2+w_1^2) (u_2^2+v_2^2+w_2^2) }}}[/tex]
replacing 1 for u₁ , 0 for v₁ and 0 for w₁ ;
also replacing 1 for u₂, 1 for v₂ and -1 for w₂ ; we have :
[tex]\lambda = cos ^{-1} [\dfrac{1*1+0*0+(0*-1)}{ \sqrt{(1^2+0^2+0^2) (1^2+0^2+(-1^2)) }}}[/tex]
[tex]\phi = cos ^{-1} [\dfrac{1}{\sqrt{2}}][/tex]
[tex]\lambda = 45^0[/tex]
The yield strength for the slip process [tex][1 0 \overline 1][/tex] can now be calculated as:
[tex]\sigma_x = \dfrac{t_{xr}}{cos \phi \ \ cos \lambda}[/tex]
where
[tex]t_{xr}[/tex] = 1.98 MPa
[tex]\sigma_x = \dfrac{1.98}{cos 54.7^0 \ \ cos 45}[/tex]
[tex]\sigma_x = \dfrac{1.98}{0.5779 *0.7071}[/tex]
[tex]\mathbf{\sigma _x = 4.85 \ MPa}[/tex]
Hence, the magnitude of the stress necessary to cause slip to occur on the (111) plane in the [tex][1 0 \overline 1][/tex] direction is 4.85 MPa
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 following statements are about the laminar boundary layer over a flat plate. For each statement, answer whether the statement is true or false.
1. At a given x-location, if the Reynolds number were to increase, the boundary layer thickness would also increase.
A. True B. False
2. As outer flow velocity increases, so does the boundary layer thickness.
A. True B. False
3. As the fluid viscosity increases, so does the boundary layer thickness.
A. True B. False
4. As the fluid density increases, so does the boundary layer thickness.
A. True B. False
5. The boundary layer equations are approximations of the Navier-Stokes equation.
A. True B. False
6. The curve representing boundary layer thickness as function of x is a streamline.
A. True B. False
7. The boundary layer approximation bridges the gap between the Euler equation and the Navier-Stokes equation.
A. True B. False
Answer:
1. B. False
2. B. False
3. A. True
4. B. False
5. A. True
6. A. True
7. A. True
Explanation:
1. B. False
The relation of Reynolds' number, Reₓ to boundary layer thickness δ at a point x is given by the relation
[tex]\delta = \dfrac{x \times C}{\sqrt{Re_x} }[/tex]
That is the boundary layer thickness is inversely proportional to the square root of the Reynolds' number so that if the Reynolds' number were to increase, the boundary layer thickness would decrease
Therefore, the correct option is B. False
2. B. False
From the relation
[tex]Re_x = \dfrac{U_o \times x}{v}[/tex]
As the outer flow velocity increases, the boundary layer thickness diminishes
3. A. True
As the viscous force is increased the boundary layer thickness increases
4. B. False
Boundary layer thickness is inversely proportional to velocity
5. A. True
The boundary layer model developed by Ludwig Prandtl is a special case of the Navier-Stokes equation
6. A. True
Given a definite boundary layer thickness, the curve representing the boundary layer thickness is a streamline
7. A. True
The boundary layer approximation by Prandtl Euler bridges the gap between the Euler (slip boundary conditions) and Navier-Stokes (no slip boundary conditions) equations.
As an engineer who has just finished taking engineering materials course, your first task is to investigate the causes of an automobile accident. Your findings show that the right rear wheel has broken off at the axle. The axle is bent. The fracture surface reveals a Chevron pattern pointing toward the surface of the axle. Suggest a possible cause for the fracture and why?
Answer is given below
Explanation:
Evidence shows that the axle was not broken before the accident, while the clumsy axle meant that the wheel was still attached when the load was applied. This indicates that the Chevron prototype wheel suffered a severe impact shock, which caused the failure of the transmission to the axle. Preliminary evidence suggests that the driver lost control and crashed. Further examination of the surface, microstructure and structure and characteristics of the fracture can be modified if the axle is properly preparedQ#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 DesignImplementationTestingDeploymentMaintenance2. The block is released from rest at the position shown, figure 1. The coefficient of
kinetic friction over length ab is 0.22, and over length bc is 0.16. Using the
principle of work and energy, find the velocity with which the block passes
position c.
Answer:
Velocity = 4.73 m/s.
Explanation:
Work done by friction is;
W_f = frictional force × displacement
So; W_f = Ff * Δs = (μF_n)*Δs
where; magnitude of the normal force F_n is equal to the component of the weight perpendicular to the ramp i.e; F_n = mg*cos 24
Over the distance ab, Potential Energy change mgΔh transforms into a change in Kinetic energy and the work of friction, so;
mg(3 sin 24) = ΔKE1 + (0.22)*(mg cos 24) *(3).
Similarly, Over the distance bc, potential energy mg(2 sin 24) transforms to;
ΔKE2 + (0.16)(mg cos 24)(2).
Plugging in the relevant values, we have;
1.22mg = ΔKE1 + 0.603mg
ΔKE1 = 1.22mg - 0.603mg
ΔKE1 = 0.617mg
Also,
0.813mg = ΔKE2 + 0.292mg
ΔKE2 = 0.813mg - 0.292mg
ΔKE2 = 0.521mg
Now total increase in Kinetic Energy is ΔKE1 + ΔKE2
Thus,
Total increase in kinetic energy = 0.617mg + 0.521m = 1.138mg
Putting 9.81 for g to give;
Total increase in kinetic energy = 11.164m
Finally, if v = 0 m/s at point a, then at point c, KE = ½mv² = 11.164m
m cancels out to give; ½v² = 11.164
v² = 2 × 11.164
v² = 22.328
v = √22.328
v = 4.73 m/s.
When using an alternative method of sizing with two vent connectors for draft hood-equipped water heaters, the effective area of the common vent connector or vent manifold and all junction fittings shall not be less than the area of the larger vent connector plus _____ percent of the areas of smaller flue collar outlets
Answer:
Fifty (50) percent. [50%]
Explanation:
Water heater is a home appliance that comprises of an electric or gas heating unit as well as a water-tank where water is heated and stored for use.
When using an alternative method of sizing with two vent connectors for draft hood-equipped water heaters, the effective area of the common vent connector or vent manifold and all junction fittings shall not be less than the area of the larger vent connector plus fifty (50) percent of the areas of smaller flue collar outlets.
A water heater is primarily vented with an approved and standardized plastic or metallic pipe such as flue or chimney, which allows gas to flow out of the water heater into the surrounding environment.
For a draft hood-equipped water heater, both the water heater and the barometric draft regulators must be installed in the same room. Also, the technician should ensure that the vent is through a concealed space such as conduit and should be labeled as Type L or Type B.
The minimum capacity of a water heater should be calculated based on the number of bathrooms, bedrooms and its first hour rating.
The throttling valve is replaced by an isentropic turbine in the ideal vapor-compression refrigeration cycle to make the ideal vapor-compression refrigeration cycle more closely approximate the actual cycle.
A. True
B. False
Answer:
False
Explanation:
The given statement is False. In real scenario the throttling valve not replaced by an isentropic turbine in the ideal vapor-compression refrigeration cycle. It is done so that the ideal vapor-compression refrigeration cycle to make the ideal vapor-compression refrigeration cycle more closely approximate the actual cycle.
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:
The exit temperature of the gas = 32° C
Explanation:
Solution
Given that:
Inlet temperature T₁ = 27°C ≈ 300.15 K
Inlet pressure P₁ = 100 KPa = 100 * 10^3 Pa
Volume flow rate , V = 15 m/s³
Diameter of the deduct, D = 500 mm = 0.5 m
Electric heater power, W heater = 130 kW = 130 * 10^3 W
The heat lost Q = 80 kW = 80 * 10^3 W
Now,
From the ideal gas law, density of the air at the inlet is given as :
ρ₁ = P₁/RT₁ = 100 * 10^3/500 * 300
=0.6667 kg/m³
The mass flow rate through the duct is computed below:
m = ρ₁ V = 0.6667 * 15 = 10 kg/s
Thus
Applying the first law of thermodynamics to the process is shown below:
Q + m (h₁ + V₁²/2 + gz₁) = m (h₂ + V₂²/2 + gz₂) + W (Conservation energy)
So,
If we neglect the potential and kinetic energy changes of the air, the above equation can be written again as:
Q + m (h₁) = m (h₂) + W
or
Q - W heater =m (h₂ - h₁) or Q - W heater =m (T₂ - T₁)
Thus
h₂ - h₁ = Cp T₂ - T₁
Now by method of substitution the known values are:
(- 80 *10^3) - (-130 * 10^3) = 10 * 100 * (T₂ -27)
Note: The heat transfer is taken as negative because the heat is lost by the gas and work done is also taken as negative because the work is done on the gas
So,
Solving for T₂,
T₂ = 32° C
Therefore the exit temperature of the gas = 32° C
5. Germanium forms a substitutional solid solution with silicon. Compute the number of germanium atoms per cubic centimeter for a germanium-silicon alloy that contains 15 wt% Ge and 85 wt% Si. The densities of pure germanium and silicon are 5.32 and 2.33 g/cm3, respectively. Atomic weight of Ge is 72.64 g/mol
Answer:
There are [tex]6.624 \times 10^{21}\,atoms[/tex] of Germanium in a germanium-silicon alloy that contains 15 wt% Ge and 85 wt% Si.
Explanation:
The masses of silicon and germanium contained in a cubic centimeter of the germanium-silicon alloy by apply the concepts of mass ([tex]m[/tex]), density ([tex]\rho[/tex]) and volume ([tex]V[/tex]), as well as the mass-mass proportion of Germanium ([tex]x[/tex]):
[tex]m_{Ge} = x \cdot \rho_{Ge}\cdot V_{sample}[/tex]
[tex]m_{Ge} = 0.15\cdot \left(5.32\,\frac{g}{cm^{3}} \right)\cdot (1\,cm^{3})[/tex]
[tex]m_{Ge} = 0.798\,g[/tex]
The amount of moles of Germanium is obtained after dividing previous outcome by its atomic weight. That is to say:
[tex]n = \frac{m_{Ge}}{M_{Ge}}[/tex]
[tex]n = \frac{0.798\,g}{72.64\,\frac{g}{mol} }[/tex]
[tex]n = 0.011\,mol[/tex]
There are 0.011 moles in a cubic centimeter of the germanium-silicon alloy. According to the Law of Avogadro, there are [tex]6.022 \times 10^{23}\,atoms[/tex] in a mole of Germanium. The quantity of atoms in a cubic centimeter is therefore found by simple rule of three:
[tex]y = \frac{0.011\,mol}{1\,mol}\times \left(6.022\times 10^{23}\,\frac{atoms}{mole} \right)[/tex]
[tex]y = 6.624 \times 10^{21}\,atoms[/tex]
There are [tex]6.624 \times 10^{21}\,atoms[/tex] of Germanium in a germanium-silicon alloy that contains 15 wt% Ge and 85 wt% Si.
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
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
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.
Air flows steadily through a variable sized duct in a heat transfer experiment with a speed of u = 20 – 2x, where x is the distance along the duct in meters, and u is in m/s. Because of heat transfer out of the duct, the air temperature, T, within the pipe cools as it goes downstream, according to T = 200 - 5x C. As they flow past the section at x= 3 meters, (a) determine the acceleration; (b) Determine the rate of change of temperature of air particles
Answer:
a) [tex]a=-28m/s^{2}[/tex]
b) [tex]\frac{dT}{dx}=-5 ^{o}C/m[/tex]
Explanation:
a)
In order to solve this problem, we need to start by remembering how the acceleration is related to the velocity of a particle. We have the following relation:
[tex]a=\frac{dv}{dt}[/tex]
in other words, the acceleration is defined to be the derivative of the velocity function with respect to time. So let's take our speed function:
u=20-2x
if we take its derivative we get:
du=-2dx
this is the same as writting:
[tex]\frac{du}{dt}=-2\frac{dx}{dt}[/tex]
we also know that velocity is defined to be:
[tex]u=\frac{dx}{dt}[/tex]
so we get that:
a=-2u
when substituting we get that:
a=-2(20-2x)
when expanding we get:
a=-40+4x
and now we can use this equation to find our acceleration at x=3, so:
a=-40+4(3)
a=-40+12
[tex]a=-28 m/s^{2}[/tex]
b)
the same applies to this problem with the difference that this will be the rate of change of the temperature per m. So we proceed and take the derivative of the temperature function:
T=200-5x
[tex]\frac{dT}{dx}=-5[/tex]
so the rate of change is [tex] -5^{o}C/m [/tex]
An insulated rigid tank is divided into two compartments of different volumes. Initially, each compartment contains the same ideal gas at identical pressure but at different temperatures and masses. The wall separating the two compartments is removed and the two gases are allowed to mix. Assuming constant specific heats, find the simplest expression for the mixture temperature written in the form
T3 = f(m1m2, m2m3, T1, T2)T 3=f( m 2m 1, m 3m 2,T 1,T 2) where m3m 3and T3T 3are the mass and temperature of the final mixture, respectively.
Answer:
Explanation:
Given that
Mass of 1 = [tex]m_1[/tex]
Mass of 2 = [tex]m_2[/tex]
Temperature in 1 = [tex]T_1[/tex]
Temperature in 2 = [tex]T_2[/tex]
Pressure remains i the group apartment
The closed system and energy balance is
[tex]E_{in}-E_{out}=\Delta E_{system}[/tex]
The kinetic energy and potential energy are negligible
since it is insulated tank ,there wont be eat transfer from the system
And there is no work involved
[tex]\Delta U = 0[/tex]
Let the final temperature be final temperature
[tex]m_1+c_v(T_3-T_1)+m_2c_v(T_3+T_2)=0\\\\m_1+c_v(T_3-T_1)=m_2c_v(T_2-T_3)---(i)[/tex]
Using mass balance
[tex]m_3+m_2+m_1[/tex]
from eqn i
[tex]m_1+c_v(T_3-T_1)=m_2c_v(T_2-T_3)m_1T_3-m_1T_1=m_2T_2-m_2T_3\\\\m_1T_3+m_2T_3=m_2T_2+m_1T_1\\\\(m_1+m_2)T_3=m_1T_1+m_2T_2\\\\(m_1)T_3=m_1T_1+m_2T_2\\\\T_3=\frac{m_1T_1_m_2T_2}{m_3}[/tex]
Therefore the final temperature can be express as
[tex]\large \boxed {T_3=\frac{m_1}{m_3} T_1+\frac{m_2}{m_3}T_2 }[/tex]
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
4. "ABC constriction Inc." company becomes the lowest in the bed process to get a $21
million construction project for "Northern Inc.". Now “ABC construction Inc." planning to
make a formal contract agreement with the "Northern Inc.". What are the main elements of
this agreement to consider it as a legal contract? Explain.
Answer is given below
Explanation:
Agreement is a official contract. It is written form or even in orally form. The Agreement can be written in formal or informal terms or we can use purely verbal language.
Agreement made between two or more party that allow the court to decide.
The main 6 elements are:
1. Offer
2. acceptance
3. consideration
4. intention to create legal relation
5. certainty
6. capacity
1. The first elements of the contract herein are ABC Sanctions Inc., without the offer, as it is not valid under the Contract Act 1950, Contract Act.
2. Once the offer is made in the contract, acceptance must take place. The agreement must be approved by Northern Inc. When Northern Inc is clear with the offer, it will accept it once the terms and conditions of the agreement are clear.
3. Contrarification is the most important aspect of a contract, when considering a contract, the other person will give something in return. It is considered an exchange between ABC Construction Inc and Northern Inc.
4. It is necessary to have these elements in the contract. Contract law 1950 is one of the requirements of a valid contract, although there is silence about the need for a legal relationship.
5. Another important aspect of the contract is of course. The Contract Agreement sets out the terms and conditions that must be clearly understood by both ABC Contracts Inc and Northern Inc.
6. The ability of a contract to have a legal capacity on either side of the contract is more than eighteen years, since the age of 18 years is specified as the age at which the contract is entered into.
The bar has a cross-sectional area of 400×10^-6 m². If it is subjected to a uniform axial distributed loading along its length and to two concentrated loads determine the average normal stress in the bar as a function of X for 0.5 m < x <= 1.25m
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.
Read more on average normal stress here: https://brainly.com/question/7958709
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 )
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