Answer:
the rate of entropy change of the air is -0.1342 kW/K
the assumptions made in solving this problem
- Air is an ideal gas.
- the process is isothermal ( internally reversible process ). the change in internal energy is 0.
- It is a steady flow process
- Potential and Kinetic energy changes are negligible.
Explanation:
Given the data in the question;
From the first law of thermodynamics;
dQ = dU + dW ------ let this be equation 1
where dQ is the heat transfer, dU is internal energy and dW is the work done.
from the question, the process is isothermal ( internally reversible process )
Thus, the change in internal energy is 0
dU = 0
given that; Air is compressed by a 40-kW compressor from P1 to P2
since it is compressed, dW = -40 kW
we substitute into equation 1
dQ = 0 + ( -40 kW )
dQ = -40 kW
Now, change in entropy of air is;
ΔS[tex]_{air[/tex] = dQ / T
given that T = 25 °C = ( 25 + 273.15 ) K = 298.15 K
so we substitute
ΔS[tex]_{air[/tex] = -40 kW / 298.15 K
ΔS[tex]_{air[/tex] = -0.13416 ≈ -0.1342 kW/K
Therefore, the rate of entropy change of the air is -0.1342 kW/K
the assumptions made in solving this problem
- Air is an ideal gas.
- the process is isothermal ( internally reversible process ). the change in internal energy is 0.
- It is a steady flow process
- Potential and Kinetic energy changes are negligible.
Problem 1. Network-Flow Programming (25pt) A given merchandise must be transported at a minimum total cost between two origins (supply) and two destinations (demand). Destination 1 and 2 demand 500 and 700 units of merchandise, respectively. At the origins, the available amounts of merchandise are 600 and 800 units. USPS charges $5 per unit from origin 1 to demand 1, and $7 per unit from origin 1 to demand 2. From origin 2 to demand 1 and 2, USPS charges the same unit cost, $10 per unit, however, after 200 units, the unit cost of transportation increases by 50% (only from origin 2 to demand 1 and 2).
a) Formulate this as a network-flow problem in terms of objective function and constraint(s) and solve using Excel Solver.
b) How many units of merchandise should be shipped on each route and what is total cost?
Solution :
Cost
Destination Destination Destination Maximum supply
Origin 1 5 7 600
Origin 2 10 10 800
15, for > 200 15, for > 200
Demand 500 700
Variables
Destination 1 2
Origin 1 [tex]$X_1$[/tex] [tex]$$X_2[/tex]
Origin 2 [tex]$X_3$[/tex] [tex]$$X_4[/tex]
Constraints : [tex]$X_1$[/tex], [tex]$$X_2[/tex], [tex]$X_3$[/tex], [tex]$$X_4[/tex] ≥ 0
Supply : [tex]$X_1$[/tex] + [tex]$$X_2[/tex] ≤ 600
[tex]$X_3$[/tex] + [tex]$$X_4[/tex] ≤ 800
Demand : [tex]$X_1$[/tex] + [tex]$$X_3[/tex] ≥ 500
[tex]$X_2$[/tex] + [tex]$$X_4[/tex] ≥ 700
Objective function :
Min z = [tex]$5X_1+7X_2+10X_3+10X_4, \ (if \ X_3, X_4 \leq 200)$[/tex]
[tex]$=5X_1+7X_2+(10\times 200)+(X_3-200)15+(10 \times 200)+(X_4-200 )\times 15 , \ \ (\text{else})$[/tex]
Costs :
Destination 1 Destination 2
Origin 1 5 7
Origin 2 10 10
15 15
Variables :
[tex]$X_1$[/tex] [tex]$$X_2[/tex]
300 300
200 400
[tex]$X_3$[/tex] [tex]$$X_4[/tex]
Objective function : Min z = 10600
Constraints:
Supply 600 ≤ 600
600 ≤ 800
Demand 500 ≥ 500
700 ≥ 500
Therefore, the total cost is 10,600.
Determine the complex power, apparent power, average power absorbed, reactive power, and power factor (including whether it is leading or lagging) for a load circuit whose voltage and current at its input terminals are given by:
Answer: hello your question is incomplete attached below is the missing detail
answer :
Complex power = 2.5 ∠ 50° VA
apparent power = 2.5 VA
average power = 1.6 Watts
reactive power = 1.915 Var
power factor = 0.64 ( leading )
Explanation:
i) complex power
P = Vrms * Irms
= 17.67∠40° * 0.1414∠-10°
= 2.5∠50° VA
ii) Apparent power
s = Vrms * Irms
= 17.67 * 0.1414
= 2.5 VA
iii) Average power absorbed
Absorbed power ( p ) = Vrms * Irms * cos∅
= 17.67 * 0.1414 * cos ( 50 )
= 1.6 watt
iv) Reactive power
P = Vrms * Irms * sin∅
= 17.67 * 0.1414 * sin ( 50 )
= 1.915 VAR
v) power factor
P.F = cos ∅ = p /s
= 1.6 watt / 2.5 VA = 0.64.
In a tension test of steel, the ultimate load was 13,100 lb and the elongation was 0.52 in. The original diameter of the specimen was 0.50 in. and the gage length was 2.00 in. Calculate (a) the ultimate tensile stress (b) the ductility of the material in terms of percent elongation
Answer:
a) the ultimate tensile stress is 66717.8 psi
b) the ductility of the material in terms of percent elongation is 26%
Explanation:
Given the data in the question;
ultimate load P = 13,100 lb
elongation δl = 0.52 in
diameter of specimen d = 0.50 in
gage length l = 2.00 inch
First we determine the cross-sectional area of the specimen
A = [tex]\frac{\pi }{4}[/tex] × d²
we substitute
A = [tex]\frac{\pi }{4}[/tex] × ( 0.50 )²
A = 0.1963495 in²
a) the ultimate tensile stress σ[tex]_u[/tex]
tensile stress σ[tex]_u[/tex] = P / A
we substitute
tensile stress σ[tex]_u[/tex] = 13,100 / 0.1963495
tensile stress σ[tex]_u[/tex] = 66717.766 ≈ 66717.8 psi
Therefore, the ultimate tensile stress is 66717.8 psi
b) ductility of the material in terms of percent elongation;
percentage elongation of specimen = [change in length / original length]100
% = [ δl / l ]100
we substitute
% = [ 0.52 in / 2.00 in ]100
= [ 0.26 ]100
= 26
Therefore, the ductility of the material in terms of percent elongation is 26%
4 An approach to a pretimed signal has 30 seconds of effective red, and D/D/1 queuing holds. The total delay at the approach is 83.33 veh-s/cycle and the saturation flow rate is 1000 veh/h. If the capacity of the approach equals the number of arrivals per cycle, determine the approach flow rate and cycle length.
Answer:
Following are the responses to the given question:
Explanation:
Effective red duration is applied each cycle r=30 second D/D/1 queuing
In total, its approach delay is 83.33 sec vehicle per cycle
Flow rate(s) of saturated = 1,000 vehicles each hour
Total vehicle delay per cycle[tex]= \frac{v \times 30^2}{2(1-\frac{v}{0.2778})}[/tex]
[tex]\to \frac{v\times 30^2}{2(1-\frac{v}{0.2778})}= 83.33\\\\\to 900v=166.66-599.928v\\\\\to v=0.111 \frac{veh}{sec}\\\\[/tex]
The flow rate for such total approach is 0.111 per second.
The overall flow velocity of the approach is 400 cars per hour
The approach capacity refers to the number of arrivals per cycle.
Environmentally friendly time ratio to cycle length:
[tex],\frac{g}{C} \ is = \frac{400}{1000}=0.4\\\\r= c-g\\\\30\ sec =C - 0.4 C\\\\C=50 \ sec[/tex]
The term variation describes the degree to which an object or idea differs from others of the same type or from a standard.
a. True
b. False
dentify the recommended practices when putting a tip on a micropipette. Select one or more: Gently push the micropipette into the tip and tap lightly to load the tip. Hold the micropipette at a 45 degree angle to the tip rack. Use the tip size designed for the micropipette size in use. Remove the tip from the rack and place it on micropipette by hand.
Answer:
Gently push the micropipette into the tip box and tag tightly to load the tip.
Explanation:
The recommended practice when putting a tip on a micropipette is ; Gently push the micropipette into the tip box and tag tightly to load the tip.
Given that it is not advisable to remove tip from rack so as not to contaminate it, if we want to put a tip on a micropipette we should gently push the micropipette into the tip box.
The National Weather Service has issued an alert for a severe storm that will bring 100 mm of rainfall in one hour. A farmer in the area is trying to decide whether to sand bag the creek that drains the 40 acres of row crops. The soil for the drainage area is a sandy clay loam and has a porosity of 0.398, effective porosity of 0.330, suction pressure of 52.3 cm, a hydraulic conductivity of 0.25 cm/hr and an effective saturation of 90%. Assuming that ponding occurs instantaneously, estimate the total depth of direct runoff in mm from the event using the Green-Ampt infiltration model.
a. 80
b. 89
c. 76
d. 72
Assuming you determine the required section modulus of a wide flange beam is 200 in3, determine the lightest beam possible that will satisfy this condition.
Answer:
W18 * 106
Explanation:
Given that the section modulus of the wide flange beam is 200 in^3 the lightest beam possible that can satisfy the section modulus must have a section modulus ≥ 200 in^3. also the value of the section modulus must be approximately closest to 200in^3
From wide flange Beam table ( showing the section modulus )
The beam that can satisfy the condition is W18 × 106 because its section modulus ( s ) = 204 in^3
explain "columnar transposition" for the transposition ciphers using the following plaintext as an example:
abcd
efgh
ijkl
mnop
Answer:
wa 4tefaw gfawe f
Explanation:
so you do e Fse gaewr gware gfawe agfawe gwar g
Discuss typical advantages and disadvantages of an irrigation system?