Answer:
30.128 days
Explanation:
Given that:
Mean = 25
Standard deviation = 4
Confidence interval = 90% = 0.9
Since the confidence interval should not exceed 90%
Then using z test table
P(z) = 0.9
For 0.8997 , we get = 1.28
For 0.9015, we get = 1.29
∴
[tex]\dfrac{0.9 - 0.8897}{0.9015 - 0.8997 }=\dfrac{ z - 1.28}{1.29 -1.28}[/tex]
By solving
Z = 1.282
Thus, the duration to be used so that it will not exceed 90% C.I is:
Z = (x - μ)/σ
1.282= ( x - 25)/4
1.282 * 4 = x - 25
(1.282*4)+25 = x
x = 30.128 days
Cody’s car accelerates from 0m/s to 45 m/s northward in 15 seconds. What is the acceleration of the car

Answer:
3 m/s²
Explanation:
Acceleration is calculated as :
a= Δv/ t
where ;
Δv = change in velocity
Δv = 45 - 0 = 45 m/s
t= 15 s
a= 45 /15
a= 3 m/s²
how do the brushes control the amount of charging an alternator does
Explanation:
Think of brushes as a sliding contact.
In an alternator the brushes provide power to the field coil which is physically mounted on the rotating shaft. They provide this direct current through two slip rings.
By controlling the power flow to the field, the power output of the alternator can be controlled. A regulator circuit is used to control the field so that the output voltage is maintained to about 13.5 to 14.5 VDC.
FUN FACT: Many brush holders have a small holes near the brush exit. When you assemble the alternator you physically push the brushes all the way into their holder and then thread a small wire through these hole. After the alternator is assembled you can pull the wire out and the brushes will snap into position.
25 points and brainiest if correct A, B, C, D
Which option identifies whether Juna's answer in the following scenario is right, and correctly explains why or why not?
The problem asks to convert 63" to its feet and inches equivalent. Juna's answer is 5' .
A. Juna's answer is correct because both the number of feet and the number of inches are correct.
B. Juna's answer is correct because although the number of inches is wrong, the number of feet is correct.
C. Juna's answer is incorrect because even though the number of feet is correct, the number of inches is wrong.
D. Juna's answer is incorrect because even though the number of inches is correct, the number of feet is wrong.
Answer:
A. Juna's answer is correct because both the number of feet and the number of inches are correct
Explanation:
The article provides information by using a list. What does it list? A. Thanksgiving food B. places where clams can be found C. birds served at the first Thanksgiving D. four men who went on a "fowling" mission
Answer:
C
Explanation:
The velocity in a channel that is 3 m deep is 1 m/s. What is the Froude number in a 1/6 scale model of that channel that satisfies dynamic similarity?a. 1.b. 0.45.c. 0.18.d. 5.4.e. 0.08.
Answer:
c. 0.18
Explanation:
The Formula for Froude Number is given as follows:
Froude No. = Inertial Forces/Gravity Forces
Froude No. = v/√(gD)
where,
v = velocity = 1 m/s
g = 9.8 m/s²
D = Depth of channel = 3 m
Therefore,
Froude No. = (1 m/s)/√[(9.8 m/s²)(3 m)]
Froude No. = 0.18
hence, the correct option will be:
c. 0.18
I can't log in even though it says all ages are accepted.Instead when I TRY logging in it says this. "We're sorry, but we are not able to complete your registration at this time". And I have tried refreshing the page and and X-ing out of the tab and restarting my computer and it doesn't work! And I know people aren't that crazy to get a account for brainly. Please help me out I really need a answer.
Answer:
Explanation:
This is not a question so to say. This is more like a complaint about how the platform works. Are you needing help with solving a personal problem or having troubles with the platform in itself
What does an environmental science and protection technician have in common with a microbiologist
Answer:
Environmental science and protection technicians both use laboratory equipment, such as microscopes, to analyze samples collected in the field. Environmental science and protection technicians also monitor the environment and investigate sources of pollution and contamination, including those affecting public health.
Hope this was helpful ;)
answer is a and b jjjjxjxjxjxjx xxxjxjxj
simple Brayton cycle using air as the working fluid has a pressure ratio of 10. The minimum and maximum temperatures in the cycle are 295 and 1240 K. Assuming an isentropic efficiency of 83 percent for the compressor and 87 percent for the turbine, determine (a) the air temperature at the turbine exit, (b) the net work output, and (c) the thermal efficiency.
Answer:
a) 764.45K
b) 210.48 kJ/kg
c) 30.14%
Explanation:
pressure ratio = 10
minimum temperature = 295 k
maximum temperature = 1240 k
isentropic efficiency for compressor = 83%
Isentropic efficiency for turbine = 87%
a) Air temperature at turbine exit
we can achieve this by interpolating for enthalpy
h4 = 783.05 kJ/kg ( calculated in the background ) at state 4 using Table A-17 for Ideal gas properties of air
T4 ( temperature at Turbine exit ) = 760 + ( 780 - 760 ) [tex](\frac{783.05-778.18}{800.13-778.18} )[/tex] = 764.45K
b) The net work output
first we determine the actual work input to compressor
Wc = h2 - h1 ( calculated values )
= 626.57 - 295.17 = 331.4 kJ/kg
next determine the actual work done by Turbine
Wt = h3 - h4 ( calculated values )
= 1324.93 - 783.05 = 541.88 kJ/kg
finally determine the network output of the cycle
Wnet = Wt - Wc
= 541.88 - 331.4 = 210.48 kJ/kg
c) determine thermal efficiency
лth = Wnet / qin ------ ( 1 )
where ; qin = h3 - h2
equation 1 becomes
лth = Wnet / ( h3 - h2 )
= 210.48 / ( 1324.93 - 626.57 )
= 0.3014 = 30.14%
A motor driven water pump operates with an inlet pressure of 96 kPa (absolute) and mass flow rate of 120 kg/min. The motor consumes 0.8 kW of electrical power, determine the maximum water pressure at the discharge of the pump.
Answer:
The maximum water pressure at the discharge of the pump (exit) = 496 kPa
Explanation:
The equation expressing the relationship of the power input of a pump can be computed as:
[tex]E _{pump,u} = \dfrac{m(P_2-P_1)}{\rho}[/tex]
where;
m = mass flow rate = 120 kg/min
the pressure at the inlet [tex]P_1[/tex] = 96 kPa
the pressure at the exit [tex]P_2[/tex] = ???
the pressure [tex]\rho[/tex] = 1000 kg/m³
∴
[tex]0.8 \times 10^{3} \ W = \dfrac{(120 \ kg/min * 1min/60 s)(P_2-96000)}{1000}[/tex]
[tex]0.8 \times 10^{3}\times 1000 = {(120 \ kg/min * 1min/60 s)(P_2-96000)}[/tex]
[tex]800000 = {(120 \ kg/min * 1min/60 s)(P_2-96000)}[/tex]
[tex]\dfrac{800000}{2} = P_2-96000[/tex]
400000 = P₂ - 96000
400000 + 96000 = P₂
P₂ = 496000 Pa
P₂ = 496 kPa
Thus, the maximum water pressure at the discharge of the pump (exit) = 496 kPa
What is different about residential construction on the local level from residential construction on the national level?
Answer:
The difference lies in the coverage of the construction. While local level construction focuses on the local area, national level construction has a nation-wide coverage.
Explanation:
Residential construction concentrates on the construction of residential buildings that have sleeping accommodations. Such constructions are opposed to the construction of other buildings that are meant for commercial uses as they lack sleeping accommodations. The federal, state, and local governments can embark on the construction of residential quarters for their residents. The constructions are also funded at the given level. When it is locally funded, the construction is meant to satisfy specific local needs. The constructions by the federal government consider the needs of many localities, and may not meet specific local needs.
Answer: A Residential construction is local in its effects even though those effects have a national impact.
Explanation:
Describe the role of C-S-H in providing strength for cement. Discuss which compounds produce C-S-H and why balancing the amounts of those compounds is important.
Answer:
Following are the solution to this question:
Explanation:
Whenever a chemical reaction occurs between water and cement the heat is released, and a [tex]CaOSiO_2H_2O[/tex] (C-S-H gel) gel constructs gel is also recognized as "tobermorite gel."
This one gel acts like a pack of gum and also has a cement quality, that holds its particles intact and therefore contributes to the overall compression mix. An increase in supply explicitly causes the movement in the outcome of power. C3S and C2S are both the compounds of Bouge that produce hydration C-S-H gel.
It mixture must be balanced as [tex]Ca(OH)_2[/tex] with C-S-H gel also is given as a byproduct. It [tex]Ca(OH)_2[/tex] , that cause sudden with sulphate and form [tex]CaSO_4[/tex] , is an unacceptable substance. Sulfate attack or later deterioration of its cement is caused by this [tex]CaSO_4[/tex] .
All C3S and C2S generate various amounts of C-S-H gel so, the required strength can be maintained without compromising on real term durability.
four subjects civil engineers need to study
Answer:
A civil engineering degree program applies mathematics and physical science to solve specific, real-world problems in commerce and industry. A strong civil engineering program typically emphasizes the practical use of geometry, trigonometry, and calculus in conjunction with physics, material science, and chemistry.
Explanation:
Hope this helps!! Please consider marking brainliest! Have a good one!!
35 points and brainiest. A, B, C, D
Which of the following identifies what carbide-tipped bits, lines on machine bolts, and lock washers all have in common?
A. All are very expensive items.
B. All are very recent inventions.
C. All are rather outdated inventions.
D. All provide an added level of strength.
Answer:c
Explanation:
An automotive fuel has a molar composition of 85% ethanol (C2H5OH) and 15% octane (C8H18). For complete combustion in air, determine: (a) the molar air-fuel ratio and air-fuel ratio by mass. (b) the lower heating value, in kJ per kmol of fuel and in kJ per kg of fuel.(c) the higher heating value, in kJ per kmol of fuel and in kJ per kg of fuel. (d) the dew point temperature of the combustion products at 1 atm, in °C. Consider a reference temperature and pressure of 25°C, 1 atm.
Answer:
a) 1
b) 1813.96 MJ/kmol
c) 32.43 MJ/kg , 1980.39 MJ/Kmol
Explanation:
molar mass of ethanol (C2H5OH) = 46 g/mol
molar mass of octane (C8H18) = 114 g/mol
therefore the moles of ethanol and octane
ethanol = 0.85 / 46
octane = 0.15 / 114
a) determine the molar air-fuel ratio and air-fuel ratio by mass
attached below
mass of air / mass of fuel = 12.17 / 1 = 12.17
b ) Determine the lower heating value
LHV of ( C2H5OH) = 26.8 * 46 = 1232.8 MJ/kmol
LHV of (C8H18). = 44.8 mj/kg * 114 kg/kmol = 5107.2 MJ/Kmol
LHV ( MJ/kmol) for fuel mixture = 0.85 * 1232.8 + 0.15 * 5107.2 = 1813.96 MJ/kmol
c) Determine higher heating value ( HHV )
HHV of (C2H5OH) = 29.7 * 46 = 1366.2 MJ/kmol
HHV of C8H18 = 47.9 MJ/kg * 114 = 5460.6 MJ/kmol
HHV in MJ/kg = 0.85 * 29.7 + 0.15 * 47.9 = 32.43 MJ/kg
HHV in MJ /kmol = 0.85 * 1366.2 + 0.15 * 5460.8 = 1980.39 MJ/Kmol
A rod with a length of L has to be made to carry load F. You need to select from the following alloys: Material Density g/cc Yield Strength, MPa AI 7075 2.81 503 AISI 4340/SAE 7.85 1160 Mg-ZK61 1.83 195 Ti8Al1Mo1V 4.37 570 Which one will have the lightest weight
Answer:
AI 7075
Explanation:
Material Density g/cc Yield strength
AI 7075 2.81 503
AISI 4340/SAE 7.85 1160
Mg-ZK61 1.83 195
Ti8A|1Mo1V 4.37 570
Determine the alloy with the lightest weight using this relationship
weight ∝ ( S / E )
E = yield strength
S = density
for AI 7075 = 2.81 / 503 = 0.00558648for AISI 4340/SAE = 7.85 / 1160 = 0.00676724for Mg-ZK61 = 1.83 / 195 = 0.00938462for Ti8A|1Mo1V = 4.37 / 570 = 0.00766667from the above calculation the alloy with the lightest weight is ;
AI 7075
What major financial flop led to the end of the Sega Dreamcast and ultimately caused Sega to stop making game consoles altogether?
1: The founder and CEO of Sega was found to be secretly skimming money off of the top of profits, leading to widespread distrust by the public and a sharp decline in sales until they ultimately had to shut down due to making no profit.
2: A small group of employees found a way to drain all of the Sega Corporation funding accounts and flee the country with all of the money, never to be heard from again.
3: A game called Shenmue, that cost more than $70 million to make, meant that everyone who owned a Dreamcast needed to buy two copies of the game just for Sega to make back the money they had spent to develop it-which didn't happen.
4: A game called Katamari Damacy that carried a virus that would infect any console that it was played on forced Sega to spend millions of dollars in refunds and bankrupted the company.
Answer:
The major financial flop that led to the end of the Sega Dreamcast and ultimately caused Sega to stop making game consoles altogether is:
3: A game called Shenmue, that cost more than $70 million to make, meant that everyone who owned a Dreamcast needed to buy two copies of the game just for Sega to make back the money they had spent to develop it-which didn't happen.
Explanation:
Shenmue, released on December 29, 1999, was created for Dreamcast by Suzuki. It was widely described as the most expensive video game ever produced. It had an estimated production and marketing cost of between US$47 and $70 million, according to the latest available data.
What simple changes would you make to a basic PID controller if you expected the sensors to be very noisy and the target to change by large steps?
Answer:
tuning the value of Ki termincreasing/changing the Kp termExplanation:
The simple change that would be made to a basic PID controller to prevent it from been noisy is tuning the value of Ki term while
The simple change that would be made to a PID controller if you want to change the target by large steps is increasing/changing the Kp term associated with the PID controller
Refrigerant-134a enters an adiabatic compressor as saturated vapor at 160 kPa at a rate of 2.4 m3/min and is compressed to a pressure of 900 kPa. Determine the minimum power that must be supplied to the compressor. Use the tables for R-134a
Answer:
11.65kWExplanation:
Step one:
given data
from the table for R-134a
For the given pressure state the following data were extracted.
s=0.94202kJ/kg.K
h1=241.14kJ/kg
∝1=0.12355m^3/kg
By interpolation, the final enthalpy and pressure with data from the table of R-134a
h2=277.12kJ/kg
The minimum power output is then determined from the energy balance
W=m(h2-h1)
W=V1/∝1(h2-h1)
W=2.4/60/0.12355(277.12-241.14)
W=0.04/0.12355(35.98)
W=0.3237(35.98)
W=11.65kW Approx.
The minimum power output of the compressor is 11.65kW
Tank has an average bearing pressure of 105 kPa. Ground water is deep. Calculate the total, pore and effective stress before tank loading and with tank
Answer:
Hello your question is incomplete attached below is the complete question
answer :
A) At 8 meters below center
Total stress = 228.827 KN/m^2
pore water pressure = 0 KN/m^2
effective stress = 228.827 - 0 = 228.827 KN/m^2
B) At 8 meters below tank edge
Total stress = 186.289 KN/m^2
pore water stress = 0 Kn/m^2
effective stress = 186.289 - 0 = 186.289 KN/m^2
Explanation:
Given data :
Diameter = 21 m
radius = 21 / 2 = 10.5 m
soil moist = 18.4 KN/cubic meter
Average bearing pressure = 105 kPa
i) Before Loading Tank
Total stress = 8 * 18.4 = 147.2 KN/m^2
Pore pressure = 0 KN/m^2
Effective stress = 147.2 - 0 = 147.2 KN/m^2
ii) After loading Tank
No change occurs
A) At 8 meters below center
Total stress = 228.827 KN/m^2
pore water pressure = 0 KN/m^2
effective stress = 228.827 - 0 = 228.827 KN/m^2
B) At 8 meters below tank edge
Total stress = 186.289 KN/m^2
pore water stress = 0 Kn/m^2
effective stress = 186.289 - 0 = 186.289 KN/m^2
attached below is the detailed solution
The water in a soil flows from Point K to Point L, a distance of 250 ft. Point K is at elevation 543 ft and Point L is at elevation 461 ft. Piezometers have been installed at both points, and their water levels are 23 ft and 74 ft, respectively, above the points. Compute the average hydraulic gradient between these two points.
Answer:
0.124
Explanation:
We calculate the hydraulic gradient by the formulas below.
I = (change in h)/(change in l)-----eqn 1
I = (hk-hl)/change in L ----- equation 2
At k the headloss = hk,
At L the headloss = hL
The distance of water travel is change in I
Total head at k
hk = 543+23
= 566 ft
Total head at L
hL = 461+74
= 535 ft
Change in L = 250
When we substitute these values in equation 2
566-535/250
= 0.124
The hydraulic gradient is 0.124
Tahir travel twice as far as ahmed, but onley one third as fast. Ahmed starts travel on tuesday at noon at point x to point z 300km, by 9:00pm. Tahir starts travel same day after 3hr of ahmed. In which time tahir reach at point z?
Answer:
6:00 pm the next day
Explanation:
Given that
Tahir traveled twice as far as Ahmed. We say,
Ahmed traveled a distance, D
Tahir would travel a distan, 2D
Tahir traveled 1/3 as fast as Ahmed, so we say
Ahmed traveled at a speed, S
Tahir would travel at a speed, S/3
If Ahmed starts travel on tuesday at noon at point x to point z 300km, by 9:00pm,
Time taken by Ahmed to travel is
9:00 pm - 12:00 pm = 9 hours
Ahmed, traveled 300 km in 9 hours, meaning he traveled at 33.3 km in an hour.
Speed, S that Ahmed traveled with is 33.3 km/h
Remember, we stated that Tahir travels at a speed of S/3, that is, The speed of Tahir is
33.3/3 = 11.1 km/h.
300 km would then be traveled in 300 km/11.1 km/h = 27 hours.
Tahir started traveling, 3 hours after Ahmed, that is 12:00 pm + 3:00 hrs = 3:00 pm, and if he's to spend 27 hours on the journey he would reach destination z at 6:00 pm the next day
Simplify the following expression: T =(AB)'B
What is the heat loss coefficient that has a symbol Uair and is found from (volumetric flow * density * specific heat capacity) of a building with a volume of 19456 cubic feet, if there is a natural air change per hour of 0.4
Answer:
Uair = 0.0749 KW/k = 74.9 W/k
Explanation:
The natural air change per hour is given by the formula:
Natural Air Change per Hour = ACPH = 60*Volume Flow/Volume
where,
ACPH = 0.4
Volume Flow = ? in ft³/min
Volume = 19456 ft³
Therefore,
0.4 = (60 min)(Volume Flow)/(19456 ft³)
Volume Flow = (0.4)(19456 ft³)/(60 min) = (129.7 ft³/min)(1 min/60 s)
Volume Flow = (2.16 ft³/s)(0.3048 m/1 ft)³ = 0.061 m³/s
Now, we find heat loss coefficient:
Uair = Volumetric Flow*Density of air*Specific Heat Capacity of air
Uair = (0.061 m³/s)(1.225 kg/m³)(1 KJ/kg.k)
Uair = 0.0749 KW/k = 74.9 W/k
How does the span of a truss relate to load-carrying capacity and when a truss fails, how much area is involved?
Answer:
For a deeper material truss, increase in distance between the top chord and bottom chord will cause the truss to bear more load with increase in Span
For Cantilever Truss ; increase in span will result in decrease in load bearing capacity of the truss
When a truss fails the areas that are affected are the supports of the truss and its corresponding spam. i.e. 4 crossbars at quarter of the span
Explanation:
The load-carrying capacity of a truss on the span is basically based on the type of truss ,
For a deeper material truss, increase in distance between the top chord and bottom chord will cause the truss to bear more load with increase in Span
For Cantilever Truss ; increase in span will result in decrease in load bearing capacity of the truss
When a truss fails the areas that are affected are the supports of the truss and its corresponding spam. i.e. 4 crossbars at quarter of the span
35 points an brainiest if correct
Which of the following nails would most likely be used in securing a delicate, decorative piece of thin wood trim to a cabinet face?
2d
10d
60d
100d
Select a Goulds 3196 pump to operate at 3560 rpm to deliver 500 gpm of water at a head of 250 ft. What impeller diameter should be installed in the pump
Answer:
Impeller diameter should be 0.02 meter
Explanation:
The Impeller diameter is a parameter with a circular design of a high speed pump. The performance of the pump depends on this parameter.
As per the given data
Speed of pump = 3,560 rpm
Rate of water flow = 500 gpm = 0.0005 m^3/minutes
Size of head = 250 ft = 250 ft x 0.3048 m/ft = 76.2 m
The impeller diameter can be calculated using following formula
Impeller diameter =0.1 x [tex]\sqrt{Water flow rate X 60}[/tex]
Impeller diameter =0.1 x [tex]\sqrt{0.0005 X 60}[/tex]
Impeller diameter =0.1 x [tex]\sqrt{0.03}[/tex]
Impeller diameter = 0.1 x 0.1732
Impeller diameter = 0.01732
Impeller diameter = 0.02 m
List the three main phases of photo interpretation in photogrammetry
Answer:
Stages of Interpretation and Mapping
Selection of photographs. Whenever possible, all photographs of a site or small area should be assessed for fitness of purpose. ...
Control points. A good spread of control points on a photograph is vital to establish the exact location or size of features. ...
Transformation.
Explanation:
What is least conducive to a rich tradition of master craftsmanship?
A. A reliance on mass production of necessary parts.
B. A demand for unique features.
C. A way for passing on knowledge of craft.
D. A respect for high craftsmanship as a kind of art.
/~\ The correct answer is:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
B. A demand for unique features.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I hope this helps! /~\
Answer:
A. A reliance on mass production of necessary parts.
Explanation:
Took the test
Select one correct statement: A) Specific ions are necessary for metals and alloys.B) An environment that causes SCC of one alloy would also causes SCC of another alloy.C) As specific ions form a film on the metal surface, hence, those ions which form films may be adequate to cause SCC.
Answer:
option C
Explanation:
The correct statement is As specific ions form a film on the metal surface, hence those ions which form films may be adequate to cause SCC
other options are wrong as ; specific ions are not necessary for metals and alloys and also an environment causing SCC for an alloy might not cause SCC of another alloy found in the environment
35 points and brainiest is it A, B, C, D
Which of the following nails would most likely be used in securing a delicate, decorative piece of thin wood trim to a cabinet face?
A. 2d
B. 10d
C. 60d
D. 100d
Answer:
c thereeeeeeeeeeeeeeeeee