Answer:
Explanation:
given data :
output voltage ( Van(t) ) = (Vd /2) + (0.85 Vd/2 sin ( w1 t ) )
w1 = 2[tex]\pi[/tex]60 rad/sec
find the value of da(t) by inputting the value of Van (t) into
da = Van(t) / Vd
hence: da(t) = 0.5 + 0.425 sin ((2[tex]\pi[/tex]60)t)
attached below is the plot of the da(t) against time
Find the power and the rms value of the following signal square: x(t) = 10 sin(10t) sin(15t)
1. Px =
2. xrmx =
Answer:
[tex]\mathbf{P_x =25 \ watts}[/tex]
[tex]\mathbf{x_{rmx} = 5 \ unit}[/tex]
Explanation:
Given that:
x(t) = 10 sin(10t) . sin (15t)
the objective is to find the power and the rms value of the following signal square.
Recall that:
sin (A + B) + sin(A - B) = 2 sin A.cos B
x(t) = 10 sin(15t) . cos (10t)
x(t) = 5(2 sin (15t). cos (10t))
x(t) = 5 × ( sin (15t + 10t) + sin (15t-10t)
x(t) = 5sin(25 t) + 5 sin (5t)
From the knowledge of sinusoidial signal Asin (ωt), Power can be expressed as:
[tex]P= \dfrac{A^2}{2}[/tex]
For the number of sinosoidial signals;
Power can be expressed as:
[tex]P = \dfrac{A_1^2}{2}+ \dfrac{A_2^2}{2}+ \dfrac{A_3^2}{2}+ ...[/tex]
As such,
For x(t), Power [tex]P_x = \dfrac{5^2}{2}+ \dfrac{5^2}{2}[/tex]
[tex]P_x = \dfrac{25}{2}+ \dfrac{25}{2}[/tex]
[tex]P_x = \dfrac{50}{2}[/tex]
[tex]\mathbf{P_x =25 \ watts}[/tex]
For the number of sinosoidial signals;
[tex]RMS = \sqrt{(\dfrac{A_1}{\sqrt{2}})^2+(\dfrac{A_2}{\sqrt{2}})^2+(\dfrac{A_3}{\sqrt{2}})^2+...[/tex]
For x(t), the RMS value is as follows:
[tex]x_{rmx} =\sqrt{(\dfrac{5}{\sqrt{2}} )^2 +(\dfrac{5}{\sqrt{2}} )^2 }[/tex]
[tex]x_{rmx }=\sqrt{(\dfrac{25}{2} ) +(\dfrac{25}{2} ) }[/tex]
[tex]x_{rmx }=\sqrt{(\dfrac{50}{2} )}[/tex]
[tex]x_{rmx} =\sqrt{25}[/tex]
[tex]\mathbf{x_{rmx} = 5 \ unit}[/tex]
In the National Electrical Code, the current carrying abilities of conductors are called the ___________.
Answer:
Ampacity
Explanation:
Ampacity is a word used to expalin ampere capacity defined by National Electrical Codes.
Ampacity is defined as the maximum current, in amperes, that can flow in a conductor continuously under the conditions of use without exceeding the temperature rating of the conductor.
Therefore, in the National Electrical Code, the current carrying abilities of conductors are called the Ampacity.
Which BEST identifies a contrast in these two passages? A) The actions taken by the bird in the poem cause injuries, but the actions taken by Sojourner Truth in the account do not cause any injuries. B) The actions taken by the bird in the poem cause no injuries, but the actions taken by Sojourner Truth in the account cause her great injuries. C) The actions taken by the bird in the poem are effective, but the actions taken by Ms. Truth, Ms. Griffling, and Ms. Haviland in the account have no impact. D) The actions taken by the bird in the poem are ineffective, but the actions taken by Ms. Truth, Ms. Griffling, and Ms. Haviland in the account have a great impact.
The option that BEST identifies a contrast in these two passages is option D) The actions taken by the bird in the poem are ineffective, but the actions taken by Ms. Truth, Ms. Griffling, and Ms. Haviland in the account have a great impact.
What do you mean by contrast?The term contrast is known to be a word that tends to show some noticeable differences between two things.
Note that it is liken to a cause and its effect. The option that BEST identifies a contrast in these two passages is option D) The actions taken by the bird in the poem are ineffective, but the actions taken by Ms. Truth, Ms. Griffling, and Ms. Haviland in the account have a great impact.
Learn more about contrast from
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The motor of an electric vehicle runs at an average of 50 hp for one hour and 25 minutes. Determine the total energy. Write the result in engineering notation and with SI units.
Answer:
The total energy of the motor of the electric vehicle is 1.902 × 10⁸ joules.
Explanation:
Power is the rate of change of work in time, since given input is average power, the total energy ([tex]\Delta E[/tex]) of the motor of the electric vehicle, measured in joules, is determined by this formula:
[tex]\Delta E = \dot W \cdot \Delta t[/tex]
Where:
[tex]\dot W[/tex] - Average power, measured in watts.
[tex]\Delta t[/tex] - Time, measured in seconds.
Now, let convert average power and time into watts and seconds, respectively:
Average Power
[tex]\dot W = (50\,hp)\times \frac{746\,W}{1\,hp}[/tex]
[tex]\dot W = 3.730\times 10^{4}\,W[/tex]
Time
[tex]\Delta t = (1\,h)\times \frac{3600\,s}{1\,h} + (25\,min)\times \frac{60\,s}{1\,min}[/tex]
[tex]\Delta t = 5.100\times 10^{3}\,s[/tex]
Then, the total energy is:
[tex]\Delta E = (3.730\times 10^{4}\,W)\cdot (5.100\times 10^{3}\,s)[/tex]
[tex]\Delta E = 1.902\times 10^{8}\,J[/tex]
The total energy of the motor of the electric vehicle is 1.902 × 10⁸ joules.
In a certain voltage-divider biased npn transistor, VB is 2.95 V. The dc emitter voltage is approximately
Answer:
2.25V
Explanation:
In the above question, we are given an npn transistor.
It's VB = Biased voltage = 2.95V
We are asked to calculate the DC emitter voltage.
DC emitter voltage = VB - VBE
Where:
VBE = Voltage between the base and emitter of a bipolar junction transistor
VBE has a set standard voltage of 0.7V
Hence,
DC emitter voltage = 2.95V - 0.7V
= 2.25V
In this exercise we have to use the knowledge of voltage to calculate the difference, like this:
[tex]2.25V[/tex]
Knowing that the initial voltage is given by 2.95V and we want to find the voltage difference we have:
[tex]DC = VB - VBE[/tex]
Where, VBE = Voltage between the base and emitter of a bipolar junction transistor is equal to 0.7 V, this way:
[tex]DC = 2.95V - 0.7V = 2.25V[/tex]
See more about voltage at brainly.com/question/2364325
A 10 mm diameter jet of water is deflected by a homogeneous rectangular block (15 mm by 200 mm by 100 mm) that weighs 6 N. Determine the minimum volume flowrate needed to tip the block.
Answer:
The minimum flow rate is [tex]2.66*10^-^4 m^3/s[/tex]Explanation:
The question is in complete without the diagram. please see attached the diagram
From the free body diagram of the block when it is ready to tip
∑M₀= 0.
kindly find attached the diagram of the rectangular block,
the free body diagram, and a detail solving for your reference
Technician A says that kinked parts should be replaced. Technician B says that bent parts may be repaired. Who is right
Answer:
Both are right
Explanation:
It all depends on the customer. The technicians job is to inform the customer about what can be done, rest depends on the customer that what he wants to be done. If he prefers to get the parts replaced then he should do it, and he he thinks that after repair they will work well then he should go for the repair.
System grounding on a power system means electrically connecting the __?__ of every wye-connected transformer or generator to earth.
Answer: Neutrals
Explanation: System grounding on a power system is a term used to describe the entire processes involved when a neutral is used as the conductor to connect to the solid earth. This ensures that power is generated. This is usually done using either an inductor, an impendance or a resistor. It is very important and necessary to carry out a proper grounding of a power system in order to ensure the safety of the equipment and the personnel etc
A homeowner consumes 260 kWh of energy in July when the family is on vacation most of the time. Determine the average cost per kWh for the month using the following residential rate schedule: Base monthly charge of $10.00. First 100 kWh per month at 16 cents/kWh. Next 200 kWh per month at 10 cents/kWh. Over 300 kWh per month at 6 cents/kWh.
Answer:
16.2 cents
Explanation:
Given that a homeowner consumes 260 kWh of energy in July when the family is on vacation most of the time.
Where Base monthly charge of $10.00. First 100 kWh per month at 16 cents/kWh. Next 200 kWh per month at 10 cents/kWh. Over 300 kWh per month at 6 cents/kWh.
For the first 100 kWh:
16 cent × 100 = 1600 cents = 16 dollars
Since 1 dollar = 100 cents
For the remaining energy:
260 - 100 = 160 kwh
10 cents × 160 = 1600 cents = 16 dollars
The total cost = 10 + 16 + 16 = 42 dollars
Note that the base monthly of 10 dollars is added.
The cost of 260 kWh of energy consumption in July is 42 dollars
To determine the average cost per kWh for the month of July, divide the total cost by the total energy consumed.
That is, 42 / 260 = 0.1615 dollars
Convert it to cents by multiplying the result by 100.
0.1615 × 100 = 16.15 cents
Approximately 16.2 cents
A signal that cannot be faked and carries the most accurate information about a situation or individual is known as an ______ signal
Answer: Honest
Explanation: In other to establish communication between two or more species, the sender and receiver, It is required of the sender to showcase certain behavior, sound or other demonstrations which are capable of passing a message to the receiver. These demonstrations are often reffered to as signals. Signals could be honest or dishonest. Honest signals are characterized by it's usefulness to the receiver and the conveyance of the actual or true meaning of underlying signal being transmitted. This is the opposite of dishonest signals which are often used to trick the receiving party as the information being transmitted are inaccurate and unreliable.
A 10 mm diameter jet of water is deflected by a homogeneous rectangular block (15 mm by 200 mm by 100 mm) that weighs 6 N. Determine the minimum volume flowrate needed to tip the block.
Answer:
the minimum volume flow rate needed to tip the block is 2.66 × 10⁻⁴ m/s
Explanation:
Given that;
diameter of the jet d = 10 mm
weight W = 6 N
Now we say
Fₓ Lfₓ - Wlw= 0
horizontal force
Fₓ = W (lw/lfₓ)
Fₓ = 6 ( 0.015/2)
Fₓ = 0.9 N
X-component of momentum
v₁p(-v₁)A₁ = - Fₓ
pA₁v₁² = Fₓ
v₁² = Fₓ / pA₁
v₁ = √( Fₓ / pA₁ )
WE SUBSTITUTE
v₁ = √ ( 0.9 / ((999)(π/4)(0.01))²
v₁ = 3.39 m/s
Now Discharge Q = A₁v₁
Q = π/4 (0.01)² (3.39)
Q = 2.66 × 10⁻⁴ m/s
therefore the minimum volume flow rate needed to tip the block is 2.66 × 10⁻⁴ m/s
How do you prevent a process B, that was forked from parent process A, from becoming a zombie? Choose one of the following:
1) By having the parent process A wait() for process B
2) By having the child process B wait() for the parent process A
3) By forking process A again, creating another child C
Answer:
3) By forking process A again, creating another child C
Explanation:
To prevent a process B, forked from a parent process A from becoming a Zombie, you have to make sure that the parent process A calls wait for every child process that terminates. We can also fork the process A again, and have the immediate child process B exited immediately.
An air-conditioning system operates at a total pressure of 1 atm and consists of a heating section and a humidifier that supplies wet steam (saturated water vapor) at 1008C. Air enters the heating section at 108C and 70 percent relative humidity at a rate of 35 m3/min, and it leaves the humidifying section at 208C and 60 percent relative humidity. Determine (a) the temperature and relative humidity of air when it leaves the heating section, (b) the rate of heat transfer in the heating section, and (c) the rate at which water is added to the air in the humidifying section.
Correct question is;
An air-conditioning system operates at a total pressure of 1 atm and consists of a heating section and a humidifier that supplies wet steam (saturated water vapor) at 100°C. Air enters the heating section at 10°C and 70 percent relative humidity at a rate of 35 m3/min, and it leaves the humidifying section at 20°C and 60 percent relative humidity. Determine (a) the temperature and relative humidity of air when it leaves the heating section, (b) the rate of heat transfer in the heating section, and (c) the rate at which water is added to the air in the humidifying section.
Answer:
A) Temperature at state 2: T2 = 19.5°C and Relative Humidity at state 2: Φ2 = 37.8%
B) Q' = 420.01 KJ/min
C) m'w = 0.1472 Kg/min
Explanation:
This question depicts a steady state process and as such the mass flow rate of dry air will remain constant during the entire process.
A) Now, from the psychometric chart attached, at temperatures of T1 = 10°C & T3 = 20°C, Relative humidities; Φ2 = 70% & Φ2 = 60% and at pressure of 1 atm, we have;
Enthalpy at state 1;h1 = 23.5 Kj/kg dry air
Absolute humidity at state 1;ω1 = ω2 = 0.0053 kg of water per kg dry air
Enthalpy at state 3;h3 = 42.3 KJ/Kg dry air
Absolute humidity at state 3; ω3 = 0.0087 kg of water per Kg dry air
Specific volume at state 1;υ1 = 0.809 m³/kg
The formula for energy balance for the humidifying is given as;
h3 = h2 + hg(ω3 - ω2)
Where hg is the enthalpy of wet steam.
From second table attached, hg at 100°C is 2675.6 KJ/kg
Thus;
Making h2 the subject, we have;
h2 = h3 + hg(ω2 - ω3)
Plugging in the relevant values we have;
h2 = 42.3 + 2675.6(0.0053 - 0.0087)
h2 = 33.2 KJ/kg
Still using the psychrometric chart attached at ω2 = 0.0053 and h2 = 33.2 KJ/kg, we have;
Temperature at state 2: T2 = 19.5°C and Relative Humidity at state 2: Φ2 = 37.8%
B) to determine the rate of heat transfer, let's first find the mass flow rate first;
m' = V1'/υ1
Thus, m' = 35/0.809
m' = 43.3 kg/min
Thus, rate of heat transfer is given by;
Q' = m'(h2 - h1)
Plugging in the relevant values, gives;
Q' = 43.3(33.2 - 23.5)
Q' = 420.01 KJ/min
C) the rate at which water is added to the air in the humidifying section is given by;
m'w = m'( ω3 - ω2)
m'w = 43.3(0.0087 - 0.0053)
m'w = 0.1472 Kg/min
Answer:
T₂ = 19.5 °C
∅₂ = 37.8%
Q = 420.01 kJ/min
m[tex]_{w}[/tex] = 0.015 kg/min
Explanation:
Given:
total pressure = p = 1 atm
Temperatures:
T₁ = 10°C
T₃ = 20°C
Relative Humidity:
∅₁ = 70%
∅₃ = 60%
Volume = V₁ = 35 m³/min
Solution:
a) Use psychometric chart to determine the enthalpies by using the given values of temperatures and relative humidity:
h₁ = 23.5 kJ/kg
w₁ = 0.0053
w₁ = w₂
h₃ = 42.3 kJ/kg
w₃ = 0.0087
v₁ = 0.809 m³/kg
When the airs flows through the heating section, the amount of moisture in it remains constant. So
w₁ = w₂
When the airs flows through the humidifying section, the amount of moisture in it increases. So
w₃ > w₂
Compute enthalpy h₂
h₂ = h₃ - ( w₃ - w₂) hs
where hs is the enthalpy of wet steam at 100°C from steam table
hs = 2676 kJ/kg
h₂ = 42.3 - ( 0.0087 - 0.0053 ) 2676
= 42.3 - (0.0034) 2676
= 42.3 - 9.0984
= 33.2016
h₂ = 33.2 kJ/kg
Compute T₂ and ∅₂
Using h₂ = 33.2 kJ/kg and w₂ = 0.0053 and psychometric chart:
T₂ = 19.5 °C
∅₂ = 37.8%
Compute mass flow rate:
mass flow rate = m = V₁ /v₁
= 35/0.809
= 43.26 kg/min
m = 43.3 kg/min
b) Compute heat transfer in the heating section:
Q = m x (h₂ - h₁)
= 43.3 kg/min ( 33.2 kJ/kg - 23.5 kJ/kg )
= 43.3 ( 9.7 )
Q = 420.01 kJ/min
c) Compute rate at which water is added to the air in the humidifying section
Let m[tex]_{w}[/tex] be the mass flow rate equation of water in humidifying section is:
m[tex]_{w}[/tex] = m(w₃ - w₂)
= 43.3 ( 0.0087 - 0.0053 )
= 43.3(0.0034)
= 0.14722
= 0.147 kg/min
m[tex]_{w}[/tex] = 0.015 kg/min
Which statement below can be used to read data from a file one character at a time?
A) inputFile.get(1)
B) inputFile.read(1)
C) inputFile.split(1)
D) inputFile.open(1)
Answer:
b
Explanation: because it says input file.read
If you measure the flow conditions (velocity, pressure, temperature) at a single point and conditions do not change over time, the flow is characterized as
Answer:
Steady flow
Explanation:
Flows in fluids can be categorized into different classes depending on the type of flow and the variations in their characteristics such as velocity, pressure, density, temperature, e.t.c
When these characteristics do not change when measured over time at a single point, then the flow is said to be steady. For a steady flow, the mathematical expression, amidst other conditions, is given as follows;
[tex]\frac{dV}{dt} = 0, \frac{dP}{dt} = 0, \frac{dT}{dt} = 0[/tex]
Where;
V, P and T are the velocity, pressure and temperature of the fluid.
PS:
Other types of flows include:
i. Unsteady flow
ii. Laminar flow
iii. Turbulent flow
iv. Uniform flow
v Non-uniform flow
vi. Rotational flow
vii. Irrotational flow
A stone-filled pit used for waste disposal is commonly referred to as a
Answer:
The answer is =Soak pit / Soakage pitAn air-conditioning system operates at a total pressure of 1 atm and consists of a heating section and a humidifier that supplies wet steam (saturated water vapor) at 1008C. Air enters the heating section at 108C and 70 percent relative humidity at a rate of 35 m3/min, and it leaves the humidifying section at 208C and 60 percent relative humidity. Determine (a) the temperature and relative humidity of air when it leaves the heating section, (b) the rate of heat transfer in the heating section, and (c) the rate at which water is added to the air in the humidifying section.
Correct question is;
An air-conditioning system operates at a total pressure of 1 atm and consists of a heating section and a humidifier that supplies wet steam (saturated water vapor) at 100°C. Air enters the heating section at 10°C and 70 percent relative humidity at a rate of 35 m3/min, and it leaves the humidifying section at 20°C and 60 percent relative humidity. Determine (a) the temperature and relative humidity of air when it leaves the heating section, (b) the rate of heat transfer in the heating section, and (c) the rate at which water is added to the air in the humidifying section.
Answer:
A) Temperature at state 2: T2 = 19.5°C and Relative Humidity at state 2: Φ2 = 37.8%
B) Q' = 420.01 KJ/min
C) m'w = 0.1472 Kg/min
Explanation:
This question depicts a steady state process and as such the mass flow rate of dry air will remain constant during the entire process.
A) Now, from the psychometric chart attached, at temperatures of T1 = 10°C & T3 = 20°C, Relative humidities; Φ2 = 70% & Φ2 = 60% and at pressure of 1 atm, we have;
Enthalpy at state 1;h1 = 23.5 Kj/kg dry air
Absolute humidity at state 1;ω1 = ω2 = 0.0053 kg of water per kg dry air
Enthalpy at state 3;h3 = 42.3 KJ/Kg dry air
Absolute humidity at state 3; ω3 = 0.0087 kg of water per Kg dry air
Specific volume at state 1;υ1 = 0.809 m³/kg
The formula for energy balance for the humidifying is given as;
h3 = h2 + hg(ω3 - ω2)
Where hg is the enthalpy of wet steam.
From second table attached, hg at 100°C is 2675.6 KJ/kg
Thus;
Making h2 the subject, we have;
h2 = h3 + hg(ω2 - ω3)
Plugging in the relevant values we have;
h2 = 42.3 + 2675.6(0.0053 - 0.0087)
h2 = 33.2 KJ/kg
Still using the psychrometric chart attached at ω2 = 0.0053 and h2 = 33.2 KJ/kg, we have;
Temperature at state 2: T2 = 19.5°C and Relative Humidity at state 2: Φ2 = 37.8%
B) to determine the rate of heat transfer, let's first find the mass flow rate first;
m' = V1'/υ1
Thus, m' = 35/0.809
m' = 43.3 kg/min
Thus, rate of heat transfer is given by;
Q' = m'(h2 - h1)
Plugging in the relevant values, gives;
Q' = 43.3(33.2 - 23.5)
Q' = 420.01 KJ/min
C) the rate at which water is added to the air in the humidifying section is given by;
m'w = m'( ω3 - ω2)
m'w = 43.3(0.0087 - 0.0053)
m'w = 0.1472 Kg/min
You are stopped at a red traffic light and are first in line at the intersection. When the traffic light changes to green, you should
Accelerate quickly up to the speed limit.
Go, regardless of other traffic. You have the right-of-way.
Go, but only if the intersection is clear. Yield to pedestrians and vehicles still in the intersection.
Answer:
Go, but only if the intersection is clear.
Explanation:
Traffic at intersection can be complicated at times. If the green light comes on after a red light, you have the right of way to go, but you should be careful to only go when the intersection is clear to avoid an accident. Once using the road, a good driver should be conscious of the other road users, as accidents might happen from you claiming your-right of-way
The city park has a stream running through it. The city wants to make better use of the park area. What steps should the city planners take to design a park that has all areas available to the public?
Answer:
they could add a play structure, with the stream they can put ducks and fish in it and picnic places
brainliest plz
Explanation:
Answer:
just took the quiz (k12) answer is...
Ask questions to identify a problem, develop a model, and carry out the plan/desgn.
Explanation:
1) Relative to electrons and electron states, what does each of the four quantum numbers specify?
2) Cite two important quantum mechanical concepts associated with the Bohr model of
the atom.
3) Cite two important additional refinements that resulted from the Wave-mechanical
atomic model.
Answer:
Cite two important additional refinements that resulted from the Wave-mechanical
atomic model.
A brittle material typically exhibits substantial plastic deformation with high energy absorption before fracture.a) trueb) false
Answer:
The answer is FALSEExplanation:
Brittle material are materials that don not undergo plastic deformation, they have very low plasticity that is while cracks can form without plastic deformation
The major/ common examples are glass, ceramics, graphite
In other words brittle materials break instead of bending, they have very low energy absorption as they don not undergo plastic deformation
Which crystal system(s) listed below has (have) the following relationship for the unit cell edge lengths?
a = b ≠ c
A. Cubic
B. Hexagonal
C. Triclinic
D. Monoclinic
E. Rhombohedral
F. Orthorhombic
G. Tetragonal
H. Both C and E
I. Both B and G
Answer:
Both B and G ( Hexagonal and Tetragonal )
Explanation:
The crystals system listed below has the following relationship for the unit cell edge lengths; a = b ≠ c ( hexagonal and Tetragonal )
hexagonal ; represents a crystal system which has three equal axes that have an angle of 60⁰ between them while Tetragonal denotes crystals that have three axes which have only two of its axes equal in length.
The option B and G that is Hexagonal and the Tetragonal are correct.
What is the Hexagonal and the Tetragonal mean?These both represent the crystal system that follows the relationships for the units of the cell edge lengths as a = b not equal to c.
The hexagonal shows the crustal system having equal access of the 60-degree angle in them. While the tetragonal shows the crystal that has three axes having two equal lengths.
Find out more information about the crystal systems.
brainly.com/question/8590454
An electrical heater 150 mm long and 5mm in diameter is inserted into a hole drilled normal to the surface of a large block of material having a thermal conductivity of 10W/mK. The temperature of the electrical heater is 70 oC and the temperature of block surface is 40 oC. Estimate the power dissipation of the electrical heater. (in W)
Explanation:
From the table of conduction shape factor and dimensionless conduction rates for selected systems, for vertical cylinder in a semi-infinite medium
[tex]S=& \frac{2 \pi L}{\ln \left(\frac{4 L}{D}\right)}[/tex]
[tex]S=& \frac{2 \pi L}{\ln \left(\frac{4 L}{D}\right)}[/tex]
[tex]\frac{2 \pi \times 0.1}{\ln \left(\frac{4 \times 0.1}{0.005}\right)}[/tex]
[tex]=0.1433 \mathrm{m}[/tex]
A hollow shaft of diameter ratio 3/8 (internal dia to outer dia) is to transmit 375 kW power at 100 rpm. The maximum torque being 20% greater than the mean torque. The shear stress is not to exceed 60 N/mm2 and twist in a length of 4m not to exceed 2o. Calculate its external and internal diameters which would satisfy both the above conditions. (G= 0.85 X 105 N/mm2)
Answer:
External diameter = 158.15 mm mm
Internal diameter = 59.31 mm
Explanation:
We are given;
Diameter ratio; d_i = ⅜d_o
Where d_i is internal diameter and d_o is external diameter
Power;P = 375 KW = 375000 W
Rotational speed;N = 100 rpm
Max torque is 20% greater than mean torque; T_max = 1.2T_avg
Shear stress;τ = 60 N/mm²
Length; L = 4m = 4000 mm
Angle of twist; θ = 2° = 2π/180 radians
Modulus of rigidity;G = 0.85 X 10^(5) N/mm²
Formula for the power transmitted by the shaft is;
P = 2πNT_avg/60
Plugging in the relevant values, we have ;
375000 = 2π × 100T_avg/60
T_avg = (375000 × 60)/(2π × 100) = 35809.862 N.m = 35809862 N.mm
Since T_max = 1.20T_avg
Thus, T_max = 1.20(35809862) = 42971834.4 N.mm
Checking for strength, we'll use;
τ = Tr/J_p
Or since r = d/2
It can be written as;
τ = T(d_o)/2J_p - - - (1)
Where T is T_max
But Polar moment of inertia of hollow shaft is;
J_p = [π(d_o)⁴ - π(d_i)⁴]/32
Now, we are told that d_i = ⅜d_o
Thus;
J_p = [π(d_o)⁴ - π(⅜d_o)⁴]/32
J_p = (π/32) × d_o⁴(1 - 3⁴/8⁴)
J_p = 0.0926 d_o⁴
Plugging this for J_p in eq 1,we have;
τ = T(d_o)/2(0.0926d_o⁴)
Making d_o the subject gives;
d_o³ = T/(2 × 0.0926τ)
Plugging in the relevant values to give;
d_o³ = 42971834.4/(2 × 0.0926 × 60)
d_o³ = 3867155.7235421166
d_o = ∛3867155.7235421166
d_o = 156.96 mm
Thus, d_i = ⅜ × 156.96 = 58.86 mm
Checking for stiffness, we'll use;
T/J_p = Gθ/L
Again T is T_max
Plugging in the relevant values, we have;
42971834.4/0.0926 d_o⁴ = (0.85 × 10^(5) × 2π/180)/4000
464058686.825054/d_o⁴ = 0.7417649321
d_o⁴ = 464058686.825054/0.7417649321
d_o⁴ = 625614216.5028806
d_o = ∜625614216.5028806
d_o = 158.15 mm
d_i = ⅜ × 158.15 = 59.31 mm
So we will pick the highest values.
Thus;
d_o = 158.15 mm
d_i = 59.31 mm
Select the correct answer.
Which of these scenarios depicts unethical workplace practice by an employee?
A.
monitoring employee movement during working hours
B. monitoring use of workplace resources
C. restricting Internet use
D. revealing confidential data
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Next
Answer:
D
Explanation:
Confidential data is not supposed to be shared amongst others.
Answer:
D.
Explanation:
Revealing confidential data is illegal first of all. And second business isn't allowed to share info due to the confidentiality law. All the others aren't unethical, they are just precautions for the safety of other employees.
An array of eight 2024 T6 aluminum alloy rectangular fins each 3 mm wide x 0.4 mm thick and 40 mm long is used to cool a transistor. When the base is 340 K and the ambient air is 300 K, how much power does the array dissipate? Take the combined convection and radiation heat transfer coefficient to be 8.0 W/m^2 K.
Answer: total heat dissipated from the array is 0.60 Watt
Explanation:
No. of fins 8
Given that:
Wdth (b) = 3 mm = 0.003 m
thickness (t) = 0.4 mm = 0.0004 m
length (L) = 40 mm
combined convection and radiation heat transfer coefficient to be = 8.0 W/m² K.
Tb = 340 K, Tw = 300 K
First we compute for area of fins A = 0.003 m × 0.00004 = 1.2 × 10⁻⁶ m²
Perimeter of Fin P = 2( 0.003 m + 0.00004 m ) = 0.0068 = 6.8 × 10⁻³
for 2024 T6 aluminium alloy K = 151 W/m-k from table
Now
m = √ ( hp/ka) = √[( 8 × 6.8 × 10⁻³ ) / (151 × 1.2 × 10⁻⁶ m²)] = 17.327
Lc = L + t/2 = 40 + 0.4/2 = 40.2 mm = 40.2 × 10⁻³
Now heat transfer from on fin :
Q = √( hpKA) × (Tb-Tw) × Tanh(mLc)
= √( 8×6.8 × 10⁻³×151×1.2 × 10⁻⁶) × (340-300) × tanh (0.6965)
= 3.13963 × 40 × 0.602144
= 0.075620 Watt
So total heat dissipated from array of 8 fins = 8 ×0.075620 = 0.60 Watt
Technician A says That drum brakes expand. Linings against a rotor to slow the vehicle. Technician b say that power brake booster reduces. the amount of force applied to the master cylinder . who is correct?
Answer:
Technician A
Explanation:
Technician A is correct. Technician B is incorrect, as the brake booster aids in the drivers ability to depress the brake pedal, but the force applied is the same if the booster was absent.
As the impurity concentration in solid solution of a metal is increased, the tensile strength:________.a) decreasesb) increasesc) remains unchanged
Answer:
Increases
Explanation:
By inhibiting the motion of dislocations by impurities in a solid solutions, is a strengthening mechanism. In solid solutions it is atomic level strengthening resulting from resistance to dislocation motion. Hence, the strength of the alloys can differ with respect to the precipitate's property. Example, the precipitate is stronger (ability to an obstacle to the dislocation motion) than the matrix and it shows an improvement of strength.
Why is it nearly impossible to obtain satisfactory performance from a shunt motor connected to an ac power source
Answer:
Because the shunt winding consist of a large number of turns,
Explanation:
It is nearly impossible to obtain satisfactory performance from a shunt motor connected to an ac power source because the shunt winding consist of a large number of turns, due to the high number of turns that the DC shunt motor has it develops a high impedance when connected to an ac power source. and due to this high impedance the amount of current that flows through the field will be very low making it nearly impossible for the shunt motor to operate properly
Three 12-V, 100-A-hr batteries are connected in series. What are the output voltage and A-hr capacity of this connection
Answer:
36V, 100A-hr
Explanation:
Since the batteries are connected in series;
i. the output voltage will be the sum of the individual voltages
ii. the current rating (A-hr) will be the same as their individual current rating (A-hr). And this is because the same current flows through the batteries.
From i,
The output voltage, V, is given by the sum of the voltages of the three batteries;
V = 12V + 12V + 12V
V = 36V
From ii,
The A-hr capacity of the connection is the same as that of the individual batteries;
100 A-hr
Therefore, the output voltage and A-hr capacity of this connection is:
36V, 100A-hr