Answer:
a) the minimum time (minutes) for the aluminium casting to solidify is 2.86 min
b) the minimum time (minutes) for the grey iron casting to solidify is 2.13 min. Therefore solidification of grey iron cast will take less time (2.13 min) compared to the solidification of the aluminium cast (2.86 min)
Explanation:
Given that; diameter of Disk = 500 mm, thickness t = 20, mold constant Cm = 2.0 sec/mm²
first we find the volume and Area;
Volume V = πD²t / 4
Volume V = π × (500)² × 20 / 4 = 3,926,991 mm³
Area A = 2πD²/ 4 + πDt
Area A = {[π × (500)²] / 2} +{ π × (500) × (20)}
Area A = 392,699.08 + 31,415.93
Area A = 424,115 mm²
a)
Chvorinov’s rule
T(aluminium) = Cm (V/A) ²
T(aluminium) = 2.0 × (3,926,991 / 424,115) ²
T(aluminium) = 171.5 s = 2.86 min
∴ the minimum time (minutes) for the casting to solidify is 2.86 min
b)
For cast iron
Cm (mold constant = 1.488 sec/mm²)
Chvorinov’s rule
T(iron) = Cm (V/A) ²
T(iron) = 1.488 × (3,926,991 / 424,115) ²
T(iron) = 127.5720s = 2.13 min
Therefore solidification of grey iron cast will take less time (2.13 min) compared to the solidification of the aluminium cast (2.86 min)
Report of invertor to convert 12 volt to 220 volt.
Input resistance of a FET is very high due to A) forward-biased junctions have high impedance B) gate-source junction is reverse-biased C) drain-source junction is reverse-biased D) none of the above
Answer:
B) gate-source junction is reverse-biased
Explanation:
FET is described as an electric field that controls the specific current and is being applied to a "third electrode" which is generally known as "gate". However, only the electric field is responsible for controlling the "current flow" in a specific channel and then the particular device is being "voltage operated" that consists of high "input impedance".
In FET, the different "charge carriers" tend to enter a particular channel via "source" and exits through "drain".
In order to enhance net radiation exchange between a high temperature surface and a low temperature surface in an enclosure, one should:________.
(A) polish both surfaces so that they are highly reflective
(B) paint both surfaces so that they are close to a blackbody surface
Answer: Option B
Explanation:
In order to enhance net radiation exchange between a high temperature surface and a low temperature surface in an enclosure, one should: paint both surfaces so that they are close to a blackbody surface but don't polish both surfaces so that they are highly reflective
Water discharging into a 10-m-wide rectangular horizontal channel from a sluice gate is observed to have undergone a hydraulic jump. The flow depth and velocity before the jump are 0.8m and 7m/s, respectively. Determine (a) the flow depth and the Froude number after the jump (b) the head loss (c) the dissipation ratio.
Answer:
A) Flow depth = 2.46 m, Froude number after jump = 0.464
B) head loss = 0.572 m
C) dissipation ratio = 0.173
Explanation:
Given data :
Velocity before jump ( v1 ) = 7 m/s
flow depth before jump ( y1 ) = 0.8 m
g = 9.81 m/s
Esi = 3.3 m ( calculated )
attached below is a detailed solution of the problem
1. In a mechanical design, it is recommended to use standard size/dimension to overcome uncertainties in stress or material strength.
A. True
B. False
2. Steels' surface fatigue strength can be correlated to their Brinell hardnesses.
A. True
B. False
3. If a material point has three principal stresses 01 = 02 = 03 = 300kpsi, then the maximum shear stress is Tmax = 150kpsi.
A. True
B. False
4. The endurance limit of a material is independent on the size of a part.
A. True
B. False
5. The tensile stress in a bolt is usually calculated through tensile force divided by area of unthreaded rod's cross-section area.
A. True
B. False
6. Edge shear-out or tear-out is one failure mode in bolted or riveted joints.
A. True
B. False
7. Pretension of bolts can be controlled by a torque wrench.
A. True
B. False
8. The material ultimate tensile strength of a spring coil is dependent on its coil diameter.
A. True
B. False
9. Adhesive joints are much stronger in tensile loading than shear loading.
A. True
B. False
10. The dominated loading condition in a helical spring is torsion along coils.
A. True
B. False
11. The principal advantage of conical springs is that the its spring rate is non-linear.
A. True
B. False
12. The dimensions of a bearing is coded by two-digit series numbers according to ABMA, one digit for width and the other one for diameter.
A. True
B. False
13. Three key things to determine selection of bearing are load, life and reliability.
A. True
B. False
14. Straight roller bearings can carry large radial loads and small amount of axial load.
A. True
B. False
15. In the AGMA method of gear analysis, gear strength values are the true material strengths.
A. True
B. False
16. A planetary gear train allows for two degrees of freedom.
A. True
B. False
Answer:
1. A.True
2. B.False
3. B.False
4. A.True
5. A.True
6. A.True
7. A.True
8. B.False
9. B.False
10. A.True
11. B.False
12. A.True
13. A.True
14. B.False
15. B.False
16. A.True
Explanation:
Most steels have endurance and fatigue limit about half the Tensile strength. Tensile strength of material is the limit of stress at which material then breaks. The tensile stress in a bolt is calculated through tensile force.
Consider a Diesel cycle that starts (at point a in Fig. 20.7) with air at temperature Ta. The air may be treated as an ideal gas. (a) If the temperature at point c is Tc, derive an expression for the efficiency of the cycle in terms of the compression ratio r. (b) What is the efficiency if Ta
Answer:
b
Explanation:
what is anythin efficiency if ta
Biết op-amp có Vsat = 12V, R1=R2=R3=R4=R, dạng sóng điện áp Vi(t) được cho như
hình 2.16b
a. Tính V0 theo Vi, độ lợi áp AV
b. Vẽ lại dạng sóng điện áp V0(t) khi Vm= 3
8 V
c. Vẽ lại dạng sóng điện áp V0(t) khi Vm = 5V
Answer:
Hello bro
Explanation:
I think i can help you something but can you translate it on english plzz
If the tank is designed to withstand a pressure of 5 MPaMPa, determine the required minimum wall thickness to the nearest millimeter using the maximum-shear-stress theory. Apply a factor of safety of 1.5 against yielding.
Answer: hello some aspects of your question is missing below is the missing information
The gas tank is made from A-36 steel and has an inner diameter of 1.50 m.
answer:
≈ 22.5 mm
Explanation:
Given data:
Inner diameter = 1.5 m
pressure = 5 MPa
factor of safety = 1.5
Calculate the required minimum wall thickness
maximum-shear-stress theory ( σ allow ) = σγ / FS
= 250(10)^6 / 1.5 = 166.67 (10^6) Pa
given that |σ| = σ allow
3.75 (10^6) / t = 166.67 (10^6)
∴ t ( wall thickness ) = 0.0225 m ≈ 22.5 mm
The phase sequence of a 3-phase system for which VAN = 120 /90o V and VBN = 120 /210o V is:_______
a) bca
b) abc
c) cab
d) acb
Answer:
b. abc
Explanation:
The phase rotation and its sequence is order in which voltage is reached to their respective sources. The wave forms of a polyphase flow through AC source to the panel. The three phase system has two possible sequence which can be a-b-c or c-b-a. The correct answer is therefore b.
Punctuate or edit the following sentences. Your punctuation and/or revisions should reflect best TW style and grammar writing practices.
1. The author an expert in cybersecurity will speak via Zoom this Wednesday.
2. Williams' book contains many illustrations, this makes it quick reading.
3. Based on the available evidence the university administrators have opted for a hybrid format for the fall quarter which begins September 20.
4. (Thesis statement) Free laptops should be offered to all students who need them.
I inferred you want literal editing of the text above.
Explanation:
Here's a correction of the sentences:
1. The author, an expert in cybersecurity will speak via Zoom on Wednesday.
In this sentence, punctuation mark ( , ) was added and the word 'this' was replaced with 'on'.
2. Williams' book contains many illustrations, which makes it easy to read.
Added punctuation and made a revision of the sentence.
3. Based on the available evidence, the university administrators have opted for a hybrid format for the fall, which begins September 20.
Mainly added punctuations to make the senstence clarer.
4. (Thesis statement) I believe Free laptops should be offered to all students who need them.
Made a few additions.
“Snow Cover Area change Analysis for Kabul Basin”
Summarize how GIS & Remote Sensing is incorporated in this study.
GIS
The full for GIS is : Geographic Information System.
The GIS is a system of mapping that is used to create, analyze, manage and map all the types of data.
It is a method capturing, checking as well as displaying all the data that is related to the position of the surface of earth.
Remote Sensing
Remote sensing is defined as a process where the various physical characteristics of an area are constantly monitored and detected by a process of measuring the reflection of the emitted radiations at ta distance.
The snow covered areas of the Kabul basin can be monitored and analyzed by using the process of GIS and remote sensing.
They provide a continuous source of information and data about snow covered peaks, the amount of snow to the authorities.
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A fixed mass of saturated water vapor at 400 kpa is isothermally cooled until it is a saturated liquid. Calculate the amount of heat rejected during this process in kJ/kg.
The amount of heat rejected during the process in kJ/kg is 2133.4 kJ/kg.
What is heat?
Heat is defined as the process of kinetic energy being transferred from an energy source to a medium or an item. These three mechanisms radiation, conduction, and convection can all transmit energy. These three modes of heat transfer are typically combined, and it often happens on its own. The heat energy can be transformed into other types of energy, such as mechanical and kinetic energy. Thermal (heat) energy is a type of energy that is produced by the movement of particles and is a component of all matter.
The process rejects a certain amount of heat, which is
-q = w + Δu
q = - w - Δu
q = - 185.5 kJ/kg - 1948.9 kJ/kg
q = 2133.4 kJ/kg
Thus, the amount of heat rejected during the process in kJ/kg is 2133.4 kJ/kg.
To learn more about heat, refer to the link below:
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The natural variation of a process relative to the variation allowed by the design specifications is known as
Answer:
"Process capability" is the correct answer.
Explanation:
The Process Capability seems to be a method of measuring of how and why the framework performs concerning something like the successful objectives. This same capacity is characterized as that of the client's voice over procedure speech.Through using functionality indicators it analyses the performance with an in-control process with the permissible range.When exchanging information with anyone involved in the collision, you should _____.
Try to be as relax as possible.
Provide names of all parties involved.
Provide vehicle information and identification details.
Provide full names, address, registration numbers and insurance company details.
Explanation:
After a collision one may be confused, afraid and have no attention about the details that what happened because all the collision event happens in a short interval of time. So the first thing one should do during information exchange is to sit back and relax and be calm so that one can remind the things at some extent. After that provide all the details about injured people and the involved vehicles.
Which of the following sentences is
punctuated incorrectly?
Answer:
Um is there suppose to be a picture with the sentences on
Answer:
It's B I did the test and I was right on B
Explanation:
I don't know I knew it was B
What is the following diagram called?
Answer:
business
Explanation:
because shopping has great income
Answer:
is ur question right
Explanation:
is ur question right
is ur question right
What is working fluid and mention five example of working fluid.
Answer:
For fluid power, a working fluid is a gas or liquid that primarily transfers force, motion, or mechanical energy. ... Examples without phase change include air or hydrogen in hot air engines such as the Stirling engine, air or gases in gas-cycle heat pumps, etc.
Explanation:
Answer:
A working fluid is a gas or liquid that primarily transfers force, motion or mechanical energy
Examples:Air, pentane, chlorofluorocarbons, butane, propane and ammonia
1. Two types of superchargers include
A. turbine and piston.
B. roots-type and centrifugal.
C. double- and single-acting
D. rotary and reciprocating.
động cơ không đồng bộ 3 pha là gì
Answer:
uhhhhhhh lemme think
Explanation:
Mention any four thermodynamic properties.
Answer:
They are pressure, temperature, volume, entropy, internal energy, enthalpy, Gibbs function and Helmholtz functions
Technician A says that when the malfunction indicator light or service engine light is on you should retrieve the diagnostic trouble code and follow the manufacturers recommended procedure. Technician B says that all obd-ll monitors must have the enabled criteria achieved before a test is performed. Who is correct?
Answer:both
Explanation:
Tech A says that a transistor has a single P–N junction. Tech B says that a transistor is a semiconductor device used as a switch and to amplify currents. Who is correct? Group of answer choices
Answer:
Both Technician A and technician B are correct.
Explanation: A transistor must have a P-N junction as that is where the positive and negative charges are connected.
A transistor also can be described as a semiconductor which acts as a switch and can be used to amplify currents. Transistors are very key and vital to electronic devices especially the mobile phones in recent times, it helps to ensure that electronic systems perform optimally.
The charges in the P-N junction is controlled by the availability of Positive and negative electrons.
what is the best book for mechanic of materials?
Answer:
As per my experience Egor Popov is one the best book for mechanics of materials.
Explanation:
hope this helps
A bona fide established commercial marketing agency is a business which is specifically devoted to public relations, advertising and promoting the services of a client. True or False
Answer:
True
Explanation:
Bona Fide is a Latin term which means in good faith or without any intention to deceive. The business established on a bona fide basis means that there is an absence of fraud. The marketing agency has devoted its services to public relations, advertising and promoting the services of clients. There is no intention of fraud in the business.
An AC generator supplies an rms voltage of 120 V at 50.0 Hz. It is connected in series with a 0.650 H inductor, a 4.80 μF capacitor and a 301 Ω resistor.
(a) What is the impedance of the circuit?
(b) What is the rms current through the resistor?
(c) What is the average power dissipated in the circuit?
(d) What is the peak current through the resistor?
(e) What is the peak voltage across the inductor?
(f) What is the peak voltage across the capacitor?
The generator frequency is now changed so that the circuit is in resonance. What is that new (resonance) frequency?
Answer:
Explanation:
f = 50.0 Hz, L = 0.650 H, π = 3.14
C = 4.80 μF, R = 301 Ω resistor. V = 120volts
XL = wL = 2πfL
= 2×3.14×50* 0.650
= 204.1 Ohm
Xc= 1/wC
Xc = 1/2πfC
Xc = 1/2×3.14×50×4.80μF
= 1/0.0015072
= 663.48Ohms
1. Total impedance, Z = sqrt (R^2 + (Xc-XL)^2)= √ 301^2+ (663.48Ohms - 204.1 Ohm)^2
√ 90601 + (459.38)^2
√ 90601+211029.98
√ 301630.9844
= 549.209
Z = 549.21Ohms
2. I=V/Z = 120/ 549.21Ohms =0.218Ampere
3. P=V×I = 120* 0.218 = 26.16Watt
Note that
I rms = Vrms/Xc
= 120/663.48Ohms
= 0.18086A
4. I(max) = I(rms) × √2
= 0.18086A × 1.4142
= 0.2557
= 0.256A
5. V=I(max) * XL
= 0.256A ×204.1
=52.2496
= 52.250volts
6. V=I(max) × Xc
= 0.256A × 663.48Ohms
= 169.85volts
7. Xc=XL
1/2πfC = 2πfL
1/2πfC = 2πf× 0.650
1/2×3.14×f×4.80μF = 2×3.14×f×0.650
1/6.28×f×4.8×10^-6 = 4.082f
1/0.000030144× f = 4.082×f
1 = 0.000030144×f×4.082×f
1 = 0.000123f^2
f^2 = 1/0.000123048
f^2 = 8126.922
f =√8126.922
f = 90.14 Hz
A four-cylinder four-stroke engine is modelled using the air standard Otto cycle (two engine revolutions per cycle). Given the conditions at state 1, total volume (V1) of each cylinder, compression ratio (r), rate of heat addition (Q), and engine speed in RPM, determine the efficiency and other values listed below. The gas constant for air is R =0.287 kJ/kg-K.
T1 = 300 K
P1 = 100 kPa
V1 = 500 cm^3
r = 10
Q = 60 kW
Speed = 5600 RPM
Required:
a. Determine the total mass (kg) of air in the engine.
b. Determine the specific internal energy (kJ/kg) at state 1.
c. Determine the specific volume (m^3/kg) at state 1.
d. Determine the relative specific volume at state 1.
Answer:
a) Mt = 0.0023229
b) = U1 = 214.07
c) = V₁ = 0.861 m³/kg
d) = Vr1 = 621.2
Explanation:
Given that
R = 0.287 KJ/kg.K, T1 = 300 K , P1 = 100 kPa , V1 = 500 cm³, r = 10 , Q = 60 kW , Speed N = 5600 RPM, Number of cylinders K = 4
specific heat at constant volume Cv = 0.7174 kJ/kg.K
Specific heat at constant pressure is 1.0045 Kj/kg.K
a) To determine the total mass (kg) of air in the engine.
we say
P1V1 = mRT1
we the figures substitute
(100 x 10³) ( 500 x 10⁻⁶) = m ( 0.287 x 10³) ( 300 )
50 = m x 86100
m = 0.00005 / 86100 = 0.0005807 ( mass of one cylinder)
Total mass of 4 cylinder
Mt = m x k
Mt = 0.0005807 x 4
Mt = 0.0023229
b) To determine the specific internal energy (kJ/kg) at state 1
i.e at T1 = 300
we obtain the value of specific internal energy U1 at 300 K ( state 1) from the table ideal gas properties of air.
U1 = 214.07
c) To determine the specific volume (m³/kg) at state 1.
we say
V₁ = V1/m
V₁ = (500 x 10⁻⁶) / 0.0005807
V₁ = 0.861 m³/kg
d) To determine the relative specific volume at state 1.
To obtain the value of relative specific volume at 300 K ( i.e state 1) from the table ideal gas properties of air.
At T1 = 300 k
Vr1 = 621.2
As the asteroid falls closer to the Earth's surface its _______ energy decreases and its _______ energy increases.
Answer:
As the asteroid falls closer to the Earth's surface its Gravitational Potential energy decreases and its Kinetic energy increases.
A steam turbine generator unit is used to produce electricity, where steam enters the turbine with a velocity of 30 m/s and enthalpy (internal energy) of 3348 kJ/kg. The 1 steam leaves the turbine as a mixture of vapor and liquid having a velocity of 60 m/s and an enthalpy of 2550 kJ/kg. The flow through the turbine is adiabatic, and changes in elevation are negligible. Determine the work output from the turbine, if the mass flow rate is 5kg/s.
Answer:
3.983 MW
Explanation:
Given that:
At the inlet:
Velocity (v₁) = 30 m/s
Enthalpy (h₁) = 3348 kJ/kg
At the outlet:
Velocity (v₂) = 60 m/s
Enthalpy (h₂) = 2550 kJ/kg
Mass flow rate (m) = m₁ = m₂ = 5kg/s
According to the steady flow energy equation:
[tex]Q+ m_1 (h_1 + \dfrac{v_1^2}{2000}+ \dfrac{gz_1}{1000} )= m_2(h_2+\dfrac{v_2^2}{2000}+\dfrac{gz_2}{1000})+W_{shaft}[/tex]
Since the elevation (z) is negligible and flow via the turbine is adiabatic:
Then,
Q = 0 and z₁ = z₂
∴
[tex]W_{shaft} = (mh_1-mh_2) + (\dfrac{mv_1^2-mv_2^2}{2000})[/tex]
[tex]W_{shaft} = ((5*3348) -(5*2550)) + (\dfrac{(5*(30)^2)-(5*(60)^2)}{2000})[/tex]
[tex]W_{shaft} = (16740-12750) + (\dfrac{4500-18000}{2000})[/tex]
[tex]W_{shaft} = (16740-12750) + (-6.75)[/tex]
[tex]W_{shaft} = 3983.25 \ kW[/tex]
[tex]\mathbf{W_{shaft} = 3.983 \ MW}[/tex]
"The transistor base-emitter voltage (VBE) a. increases with an increase in temperature. b. is not affected by temperature change. c. decreases with an increase in temperature. d. has no effect on collector current."
Answer:
C) Decreases with an increase in temperature
Explanation:
As the temperature of a transistor increases, the thermal runaway property of the transistor becomes more significant and the transistors, conducting more freely as a result of the rise in temperature, causes an increase in the collector current or leakage current. The transistor base-emitter voltage decreases as a result.
With increased heating due to heavy current flow, the transistor is damaged.
Suppose we have 999 records of employees Emp1, Emp2, Emp5, Emp6 and so on up to Emp998 and Emp999 stored in a sequence. Hence, records are nothing but a row in the table. In the employee table, we want to insert new records Emp3 and Emp4 in the sequence, and once we have done insertion we need to update and retrieve the record efficiently to optimize the performance of a database by minimizing the access time when query is being executed.
The records in the table represents the employee ID of each employee. Assume the table name is EMPLOYEES and the field name of employee IDs is ID, the following SQL query inserts Emp3 and Emp4 into the employees table.
INSERT INTO EMPLOYEES (ID) values (Emp3), (Emp4)
The complete question requires that we list the pros and cons of solving the problem using Index sequential access method (ISAM).
The advantage of using ISAM is that priorities are given to the indices of the records being inserted. So, Emp3 and Emp4 will be inserted immediately after Emp2.
However, a major disadvantage of using ISAM is that it is very expensive to keep the indices in a sequential order;
See attachment for the illustration of Index sequential access method (ISAM).
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