Answer:
Yes, it is true
Explanation:
The computation of the time required to cool the water is shown below:
GIven that
Average cop = 2.8
Therefore the cooling effect is
= 2.8 × 400 W
= 1,120 W
ANd, the specific heat of water is 4.2 kj/kg°C i.e 4,200 j/kg°C
Now we assume the time is t
As we know that
[tex]1,120 \times t = 10\times 4,200 \times (40 - 10)\\\\ therefore\\\\ t = \frac{10\times4,200\times30}{1,120}[/tex]
t = 1,125 seconds
So, it would be 19 minutes
Therefore it is true
Which greenhouse gas is produced by commercial refrigeration and air conditioning systems?
carbon dioxide
Ofluorinated gas
O nitrous oxide
O methane
Answer:
B- Fluorinated gas
Explanation:
Answer:
B.) fluorinated gas
Explanation:
what is the difference between erratic error and zero error
The negative mark is balanced by a positive mark on the set key scale while the jaws are closed.
It is common practice to shut the jaws or faces of the system before taking some reading to guarantee a zero reading. If not, please take care of the read. This read is referred to as "zero defect."
There are two forms of zero error:
zero-mistake positive; and
Non-null mistake.
----------------------------
Hope this helps!
Brainliest would be great!
----------------------------
With all care,
07x12!
A two-dimensional flow field described by
V = (2x^2y + x)1 + (2xy^2 + y + 1 )j
where the velocity is in m/s when x and y are in meters. Determine the angular rotation of a fluid element located at x 0.5 m, y 1.0 m.
Answer:
the answer is
Explanation:
We now focus on purely two-dimensional flows, in which the velocity takes the form u(x, y, t) = u(x, y, t)i + v(x, y, t)j. (2.1) With the velocity given by (2.1), the vorticity takes the form ω = ∇ × u = ∂v ∂x − ∂u ∂y k. (2.2) We assume throughout that the flow is irrotational, i.e. that ∇ × u ≡ 0 and hence ∂v ∂x − ∂u ∂y = 0. (2.3) We have already shown in Section 1 that this condition implies the existence of a velocity potential φ such that u ≡ ∇φ, that is u = ∂φ ∂x, v = ∂φ ∂y . (2.4) We also recall the definition of φ as φ(x, y, t) = φ0(t) + Z x 0 u · dx = φ0(t) + Z x 0 (u dx + v dy), (2.5) where the scalar function φ0(t) is arbitrary, and the value of φ(x, y, t) is independent of the integration path chosen to join the origin 0 to the point x = (x, y). This fact is even easier to establish when we restrict our attention to two dimensions. If we consider two alternative paths, whose union forms a simple closed contour C in the (x, y)-plane, Green’s Theorem implies thatWhat is the criteria for a guard having to be used on a machine?
The criteria for a guard having to be used on a machine is;
As a safety measure If the operation exposes you to an injury.
When operating a machine, there are possibilities that the operator could be injured or exposed to injury.
Due to the possible safety issues when operating a machine, the Occupational Safety and Health Administration (OSHA) in their 29 code mandated that a safeguard must be put at each machine to ensure that there is adequate safety that prevents or minimizes the risk of getting injured.
Read more on Occupational Safety and Health Administration (OSHA) rules at; https://brainly.com/question/17069021
A gear motor can develop 2 hp when it turns at 450rpm. If the motor turns a solid shaft with a diameter of 1 in., determine the maximum shear stress developed in the shaft. (30 pts)
Answer:
Maximum shear stress is;
τ_max = 1427.12 psi
Explanation:
We are given;
Power = 2 HP = 2 × 746 Watts = 1492 W
Angular speed;ω = 450 rev/min = 450 × 2π/60 rad/s = 47.124 rad/s
Diameter;d = 1 in
We know that; power = shear stress × angular speed
So,
P = τω
τ = P/ω
τ = 1492/47.124
τ = 31.66 N.m
Converting this to lb.in, we have;
τ = 280.2146 lb.in
Maximum shear stress is given by the formula;
τ_max = (τ•d/2)/J
J is polar moment of inertia given by the formula; J = πd⁴/32
So,
τ_max = (τ•d/2)/(πd⁴/32)
This reduces to;
τ_max = (16τ)/(πd³)
Plugging in values;
τ_max = (16 × 280.2146)/((π×1³)
τ_max = 1427.12 psi
A square concrete column is 4 in by 4 in cross-section and is subject to a compressive load P. If the compressive stress cannot exceed 4000 psi and the shear stress cannot exceed 1500 psi, the maximum allowable load P is most nearly:
Answer:
64000 lb
Explanation:
A square concrete column is 4 in by 4 in cross-section and is subject to a compressive load P. If the compressive stress cannot exceed 4000 psi and the shear stress cannot exceed 1500 psi.
The area of the square concrete column = 4 in × 4 in = 16 in²
The compressive stress (σ) cannot exceed 4000 psi.
Compressive stress is the ratio of load applied to the area. Therefore the maximum load is the product of the maximum compressive stress and the area. The maximum compressive stress is given as:
[tex]\sigma_{max}=\frac{P_{max}}{Area} \\P_{max}= \sigma_{max}*Area\\P_{max}=4000\ psi *16\ in^2\\P_{max}=64000\ lb[/tex]
Therefore the maximum allowable load P is 64000 lb
Technician A says that the micrometer operates on a simple principle: The spindle has 20 threads per inch, so one revolution of the thimble will advance or retract the spindle 1/20 of an inch. Technician B says that spindle has 50 threads per inch, so one revolution of the thimble will advance or retract the spindle 1/50 of an inch. Who is correct
Answer:
Explanation:
neither of the technicians is correct
A complex Brayton-cycle power plant using intercooling, reheat, and regeneration is analyzed using the cold air standard method. Air is compressed from State 1 to State 2 using a compressor with a pressure ratio of RP1. An intercooler is used to cool the air to State 3 before entering a second compressor with a pressure ratio of RP2. The compressed air exits at State 4 and is preheated in a regenerator that uses the exhaust air from the low pressure turbine. The preheated air enters the combustor at State 5 and is heated to State 6 where it enters the high pressure turbine. The air exits the turbine at State 7 and is heated in a reheat combustor to State 8. The air expands in a low pressure turbine to State 9 where it enters the counterflow regenerator with an effectiveness of RE. Given the specified operating conditions determine the efficiency and other values listed below. The specific heat ratio and gas constant for air are given as k
[tex]
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Time Picker</title>
</head>
<body>
<!--24 Hours format-->
<input type="time" placeholder="Enter Time" />
<input type="date">
</body>
</html>
[/tex]
When checking the resistance of a dual voltage wye motor, there should be ____ resistance readings. 1) twelve 2) six 3) three
Answer:
1) twelve
Explanation:
The dual voltage motors are used in day to day operations. The wye is connected with 9 lead motors. Maximum resistance can be obtained if the resistance are connected in series. To check resistance of dual voltage wye motor there must be twelve resistance readings of 1 ohm each.
Technician A says that hot spots on the flywheel are a result of excessive heat. Technician B says that a pulsation in a clutch pedal could be due to uneven clutch pressure plate levers. Who is correct?
Answer:
Both Technicians A and B are correct
Explanation:
When there is excessive heat generation within the engine otherwise referred to as engine overheating which may be due combination of many factors such as cooling system problem, low level of lubricant or leakage, e.t.c, hot spots is observed in the flywheel.
Also, pulsation in a clutch pedal could be caused due to uneven clutch pressure plate levers. He clutch pressure should at all time be constant to ensure proper functioning of clutch pedal to encourage smooth drive.
how does a TV'S screen work
Answer:
A TVS screen works when the pixels are switched on electronically using liquid crystals to rotate polarized light.
Explanation:
An 800-W iron is left on the iron board with its base exposed to the air at 20°C. The convection heat transfer coefficient between the base surface and the surrounding air is 35 W/m2·K. If the base has an emissivity of 0.6 and a surface area of 0.02 m2, determine the temperature of the base of the iron.
Answer:
874.5 K
Explanation:
See attachment
The output S/N at thereceiver must be greater than 40 dB. The audio signal has zero mean, maximum amplitude of 1, power of ½ Wand bandwidth of 15 kHz. The power spectral density of white noise N0/2 = 10-10W/Hz and the power loss in the channel is 50 dB. Determine the transmit power required and the bandwidth needed.
Given that,
The output signal at the receiver must be greater than 40 dB.
Maximum amplitude = 1
Bandwidth = 15 kHz
The power spectral density of white noise is
[tex]\dfrac{N}{2}=10^{-10}\ W/Hz[/tex]
Power loss in channel= 50 dB
Suppose, Using DSB modulation
We need to calculate the power required
Using formula of power
[tex]P_{L}_{dB}=10\log(P_{L})[/tex]
Put the value into the formula
[tex]50=10\log(P_{L})[/tex]
[tex]P_{L}=10^{5}\ W[/tex]
For DSB modulation,
Figure of merit = 1
We need to calculate the input signal
Using formula of FOM
[tex]FOM=\dfrac{\dfrac{S_{o}}{N_{o}}}{\dfrac{S_{i}}{N_{i}}}[/tex]
[tex]1=\dfrac{\dfrac{S_{o}}{N_{o}}}{\dfrac{S_{i}}{N_{i}}}[/tex]
[tex]\dfrac{S_{i}}{N_{i}W}=\dfrac{S_{o}}{N_{o}}[/tex]
Put the value into the formula
[tex]\dfrac{S_{i}}{2\times10^{-10}\times15\times10^{3}}<40\ dB[/tex]
[tex]\dfrac{S_{i}}{30\times10^{-7}}<10^{4}[/tex]
[tex]S_{i}<30\times10^{-3}[/tex]
[tex]S_{i}=30\times10^{-3}[/tex]
We need to calculate the transmit power
Using formula of power transmit
[tex]S_{i}=\dfrac{P_{t}}{P_{L}}[/tex]
[tex]P_{t}=S_{i}\times P_{L}[/tex]
Put the value into the formula
[tex]P_{t}=30\times10^{-3}\times10^{5}[/tex]
[tex]P_{t}=3\ kW[/tex]
We need to calculate the needed bandwidth
Using formula of bandwidth for DSB modulation
[tex]bandwidth=2W[/tex]
Put the value into the formula
[tex]bandwidth =2\times15[/tex]
[tex]bandwidth = 30\ kHz[/tex]
Hence, The transmit power is 3 kW.
The needed bandwidth is 30 kHz.
Tech A says that a gear set that has a drive gear with 9 teeth and a driven gear with 27 teeth has a gear ratio of 3:1. Tech B says that the drive gear is also called the output gear. Who is correct?
Answer:
Tech A is correct.
Explanation:
Gears are toothed wheels that can be used to transmit power. When two or more gears are in tandem, a gear train is formed.
Gear ratio = [tex]\frac{number of teeth of the driven gear}{Number of teeth of the driving gear}[/tex]
= [tex]\frac{27}{9}[/tex]
= [tex]\frac{3}{1}[/tex]
Gear ratio = 3:1
The driver gear is called the input gear since it transfers its power to the driven gear. While the driven gear is called the output gear because it produces an effect due to both gears.
Tech A is correct.
Air flows along a horizontal, curved streamline with a 20 foot radius with a speed of 100 ft/s. Determine the pressure gradient normal to the streamline.
Answer:
- 1.19 lb/ft^3
Explanation:
You are given the following information;
Radius r = 20 ft
Speed V = 100 ft/s
You should use Bernoulli equation pertaining to streamline. That is, normal to streamline.
The pressure gradient = dp/dn
Where air density rho = 0.00238 slugs per cubic foot.
Please find the attached files for the solution and diagram.
A 1/150 scale model is to be usedin a towing tank to study the water motion near the bottom of a shallow channel as a large barge passes over. (See Video V7.16.) Assume that the model is operated in accordance with the Froude number criteria for dynamic similitude. The prototype barge moves at a typical speed of 15 knots. (a) At what speed (in ft/s) should the model be towed
Answer:
The speed will be "3.58 ft/s". The further explanation is given below.
Explanation:
Number of knots
= 15
For the similarity of Froude number:
⇒ [tex]\frac{V_{m}}{\sqrt{g_{m}l_{m}} }=\frac{V}{\sqrt{gl} }[/tex]
Here,
[tex]l = length[/tex]
[tex]g_{m}=g[/tex]
⇒ [tex]\frac{V_{m}}{V}=\sqrt{\frac{l_{m}}{l} }[/tex]
[tex]V_{m}=\sqrt{\frac{1}{50} }\times number \ of \ knots[/tex]
[tex]=\sqrt{\frac{1}{50}}\times 15[/tex]
[tex]=2.12 \ knots[/tex]
Now,
⇒ [tex]1 \ knots=0.514\times 3.281[/tex]
[tex]=1.69 \ ft/s[/tex]
So that,
⇒ [tex]V_{m}=2.12\times 1.69[/tex]
[tex]=3.58 \ ft/s[/tex]
Instructions given by traffic police or construction flaggers _____. A. Are sometimes important to follow B. Are usually not important to follow C. Don't overrule laws or traffic control devices D. Overrule any other laws and traffic control devices
Answer:
D. Overrule any other laws and traffic control devices.
Explanation:
Laws and traffic control devices are undoubtedly compulsory to be followed at every point in time to control traffic and other related situations. However, there are cases when certain instructions overrule these laws and traffic control devices. For example, when a traffic police is giving instructions, and though the traffic control devices too (such as traffic lights) are displaying their own preset lights to control some traffic, the instructions from the traffic police take more priority. This is because at that point in time, the instructions from the traffic control devices might not be just applicable or sufficient.
Also, in the case of instructions given by construction flaggers, these instructions have priority over those from controlling devices. This is because during construction traffic controls are redirected from the norms. Therefore, the flaggers such be given more importance.
Answer:
D. Overrule any other laws and traffic control devices.
Explanation:
Suppose a student carrying a flu virus returns to an isolated college campus of 9000 students. Determine a differential equation governing the number of students x(t) who have contracted the flu if the rate at which the disease spreads is proportional to the number of interactions between students with the flu and students who have not yet contracted it. (Usek > 0for the constant of proportionality and x forx(t).)
Answer:
dx/dt = kx(9000-x) where k > 0
Explanation:
Number of students in the campus, n = 9000
Number of students who have contracted the flu = x(t) = x
Number of students who have bot yet contracted the flu = 9000 - x
Number of Interactions between those that have contracted the flu and those that are yet to contract it = x(9000 - x)
The rate of spread of the disease = dx/dt
Note: the rate at which the disease spread is proportional to the number of interactions between those that have contracted the flu and those that have not contracted it.
[tex]\frac{dx}{dt} \alpha [x(9000 -x)]\\[/tex]
Introducing a constant of proportionality, k:
dx/dt = kx(9000-x) where k > 0
Under conditions for which the same room temperature is maintained by a heating or cooling system, it is not uncommon for a person to feel chilled in the winter but comfortable in the summer. Provide a plausible explanation for this situation (with supporting calculations) by considering a room whose air temperature is maintained at 20 ℃ throughout the year, while the walls of the room are nominally at 27 ℃ and 14 ℃ in the summer and winter, respectively. The exposed surface of a person in the room may be assumed to be at a temperature of 32 ℃ throughout the year and to have an emissivity of 0.90. The coefficient associated with heat transfer by natural convection between the person and the room air is approximately 2 W/m2∙K.
Answer:
radiative heat loss substantially increases as the wall temperature declines
Explanation:
The body's heat loss due to convection is ...
(2 W/m^2·K)((32 -20)K) = 24 W/m^2
__
The body's heat loss due to radiation in the summer is ...
[tex]\epsilon\sigma(T_b^4-T_w^4)\quad\text{where $T_b$ and $T_w$ are body and wall temperatures ($^\circ$K)}\\\\0.90\cdot 5.6703\cdot 10^{-8}(305.15^4-300.15^4)\,\text{W/m$^2$}\\\\\approx 28.3\,\text{W/m$^2$}[/tex]
The corresponding heat loss in the winter is ...
[tex]0.90\cdot 5.6703\cdot 10^{-8}(305.15^4-287.15^4)\,\text{W/m$^2$}\\\\\approx 95.5\,\text{W/m$^2$}[/tex]
Then the total of body heat losses to surroundings from convection and radiation are ...
summer: 24 +28.3 = 52.3 . . . W/m^2
winter: 24 +95.5 = 119.5 . . . W/m^2
__
It is reasonable that a person would feel chilled in the winter due to the additional radiative loss to the walls in the winter time. Total heat loss is more than doubled as the wall temperature declines.
For laminar flow over a hot flat plate, the local heat transfer coefficient decreases with distance because (select all that are correct
Answer:
hello the answer options are missing here are the options
A)The thickness of the heated region near the plate is increasing
B)The velocities near the plates are increasing
C)The fluid temperature near the plate are increasing
ANSWER : all of the above
Explanation:
Laminar flow is the flow of a type of fluid across the surface of an object following regular paths and it is unlike a turbulent flow which flows in irregular paths (encountering fluctuations)
For laminar flow over a hot flat plate, the local heat transfer coefficient decreases with distance because :
The thickness of the heated region near the plate is increasingThe velocities near the plates are increasingThe fluid temperature near the plate are increasingAn air-standard Diesel cycle has a compression ratio of 16 and a cutoff ratio of 2. At the beginning of the compression process, air is at 95 kPa and 27 degree Celsius.
(a) Determine the temperature after the heat-addition process.
(b) Determine the thermal efficiency.
(c) Determine the mean effective pressure. Solve the problem in the constant heat supposition.
Answer:
a) T₃ = 1818.8 K
b) η = 0.614 = 61.4%
c) MEP = 660.4 kPa
Explanation:
a) According to Table A-2 of The ideal gas specific heat of gases, the properties of air are as following:
At 300K
The specific heat capacity at constant pressure = [tex]c_{p}[/tex] = 1.005 kJ/kg.K,
The specific heat capacity at constant volume = [tex]c_{v}[/tex] = 0.718 kJ/kg.K
Gas constant R for air = 0.2870 kJ/kg·K
Ratio of specific heat k = 1.4
Isentropic Compression :
[tex]T_{2}[/tex] = [tex]T_{1}[/tex] [tex](v1/v2)^{k-1}[/tex]
= 300K ([tex]16^{0.4}[/tex])
[tex]T_{2}[/tex] = 909.4K
P = Constant heat Addition:
[tex]P_{3}v_{3} / T_{3} = P_{2} v_{2} /T_{2}[/tex]
[tex]T_{3}=v_{3}/v_{2}T_{2}[/tex]
2[tex]T_{2}[/tex] = 2(909.4K)
= 1818.8 K
b) [tex]q_{in}[/tex] = [tex]h_{3}-h_{2}[/tex]
= [tex]c_{p}[/tex] ([tex]T_{3}[/tex] - [tex]T_{2}[/tex])
= (1.005 kJ/kg.K)(1818.8 - 909.4)K
= 913.9 kJ/kg
Isentropic Expansion:
[tex]T_{4}[/tex] = [tex]T_{3}[/tex] [tex](v3/v4)^{k-1}[/tex]
= [tex]T_{3}[/tex] [tex](2v_{2} /v_{4} )^{k-1}[/tex]
= 1818.8 K (2 / 16[tex])^{0.4}[/tex]
= 791.7K
v = Constant heat rejection
[tex]q_{out}[/tex] = μ₄ - μ₁
= [tex]c_{v} ( T_{4} - T_{1} )[/tex]
= 0.718 kJ/kg.K (791.7 - 300)K
= 353 kJ/kg
η[tex]_{th}[/tex] = 1 - [tex]q_{out}[/tex] / [tex]q_{in}[/tex]
= 1 - 353 kJ/kg / 913.9 kJ/kg
= 1 - 0.38625670
= 0.6137
= 0.614
= 61.4%
c) [tex]w_{net}._{out}[/tex] = [tex]q_{in}[/tex] - [tex]q_{out}[/tex]
= 913.9 kJ/kg - 353 kJ/kg
= 560.9 kJ/kg
[tex]v_{1} = RT_{1} /P_{1}[/tex]
= (0.287 kPa.m³/kg/K)*(300 K) / 95 kPa
= 86.1 / 95
= 0.9063 m³/kg = v[tex]_{max}[/tex]
[tex]v_{min} =v_{2} = v_{max} /r[/tex]
Mean Effective Pressure = MEP = [tex]w_{net,out}/v_{1} -v_{2}[/tex]
= [tex]w_{net,out}/v_{1}(1-1)/r[/tex]
= 560.9 kJ/kg / (0.9063 m³/kg)*(1-1)/16
= (560.9 kJ / 0.8493m³) (kPa.m³/kJ)
= 660.426 kPa
Mean Effective Pressure = MEP = 660.4 kPa
The temperature after the addition process is 1724.8k, the thermal efficiency of the engine is 56.3% and the mean effective pressure is 65.87kPa
Assumptions made:
The air standard assumptions are madeThe kinetic and potential energy changes are negligibleThe air in the system is an ideal gas with variable or different specific heat capacity.a) The temperature after the addition process:
Considering the process 1-2, Isentropic expansion
at
[tex]T_1=300k\\u_1=214.07kJ/kg\\v_o_1=621.3\\v_o_2=\frac{v_2}{v_1} *v_o_1[C.R=16]=v_2/v_1\\v_o_2=(v_2/v_1)v_o_1=1/16*621.2=38.825[/tex]
From using this value, v[tex]_o_2[/tex]=38.825, solve for state point 2;
[tex]T_2=862.4k\\h_2=890.9kJ/kg[/tex]
Considering the process 2-3 (state of constant heat addition)
[tex]\frac{p_3v_3}{t_3}=\frac{p_2v_2}{t_2} \\\\T_3=\frac{P_3V_3T_2}{V_2} \\T_3=(\frac{V_3}{V_2}) T_2\\\frac{v_3}{v_2}=2\\T_3=2(862.4)=1724.8k\\[/tex]
NB: p[tex]_3[/tex]≈p[tex]_2[/tex]
b) The thermal efficiency of the engine is
Q[tex]_i_n[/tex]=h[tex]_3-h_2[/tex] = 1910.6-890.9=1019.7kJ/kg
Considering process 3-4,
[tex]v_o_4=\frac{v_A}{v_2}\\ v_o_3 =\frac{V_a}{V_2}*\frac{v_2}{v_3}\\v_o_3=\frac{16}{2}*4.546\\v_o_3=36.37;v_4=659.7kJ/kg[/tex]
Q[tex]_o_u_t=v_4-u_1=659.7-214.07=445.3kJ/kg[/tex]
nth = [tex]1-\frac{Q_o_u_t}{Q_i_n}=1-\frac{445.63}{1019.7}=0.5629*100=56.3%[/tex]%
The thermal efficiency is 56.3%
W[tex]_n_e_t[/tex]=[tex]Q_i_n-Q_o_u_t=574.07kJ/kg[/tex]
[tex]v_1=\frac{RT_1}{p_1}=\frac{0.287*300}{95}=0.906m^3/kg\\v_2=v_1/16=0.05662m^3/kg\\[/tex]
Therefore, the mean effective pressure of the system engine is
[tex]\frac{W_n_e_t}{v_1-v_2}=675.87kPa[/tex]
The mean effective pressure is 65.87kPa as calculated above
Learn more about mean effective pressure
https://brainly.com/question/19309495
A rectangular steel bar 37.5 mm wide and 50 mm thick is pinned at each end and subjected to axial compression. The bar has a length of 1.75 m. The modulus of elasticity is 200 Gpa. What is the critical buckling load
Answer:
The critical buckling load is [tex]\mathbf{P_o = 141.61 \ kN}[/tex]
Explanation:
Given that:
the width of the rectangular steel = 37.5 mm = 0.0375 m
the thickness = 50 mm = 0.05 m
the length = 1.75 m
modulus of elasticity = 200 Gpa = 200 10⁹ × Mpa
We are to calculate the critical buckling load [tex]P_o[/tex]
Using the formula:
[tex]P_o = \dfrac{\pi ^2 E I}{L^2}[/tex]
where;
[tex]I = \dfrac{0.0375^3*0.05}{12}[/tex]
[tex]I = 2.197 * 10^{-7}[/tex]
[tex]P_o = \dfrac{\pi ^2 *200*10^9 * 2.197*10^{-7}}{1.75^2}[/tex]
[tex]P_o = 141606.66 \ N[/tex]
[tex]\mathbf{P_o = 141.61 \ kN}[/tex]
The critical buckling load is [tex]\mathbf{P_o = 141.61 \ kN}[/tex]
A truss is subjected to three loads. The truss is supported by a roller at A and by a pin joint at B. What is most nearly the reaction force at B
Answer:
Hello the diagram related to the question is missing attached is the diagram
Answer : 3833.33 KN
Explanation:
The most nearly reaction force at B
= ∑ Mb = 0 = 21Ay
= (2000 * 17.5 ) + ( 3000 * 10.5 ) + ( 4000 * 3.5 )
= 35000 + 31500 + 14000 = 80500
therefore Ay = 80500 / 21 = 3833.33 KN
x = 7/2 = 3.5m
Consider fully developed laminar flow in a circular pipe. If the viscosity of the fluid is reduced by half by heating while the flow rate is held constant, how will the pressure drop change
Answer:
The pressure drop across the pipe also reduces by half of its initial value if the viscosity of the fluid reduces by half of its original value.
Explanation:
For a fully developed laminar flow in a circular pipe, the flowrate (volumetric) is given by the Hagen-Poiseulle's equation.
Q = π(ΔPR⁴/8μL)
where Q = volumetric flowrate
ΔP = Pressure drop across the pipe
μ = fluid viscosity
L = pipe length
If all the other parameters are kept constant, the pressure drop across the circular pipe is directly proportional to the viscosity of the fluid flowing in the pipe
ΔP = μ(8QL/πR⁴)
ΔP = Kμ
K = (8QL/πR⁴) = constant (for this question)
ΔP = Kμ
K = (ΔP/μ)
So, if the viscosity is halved, the new viscosity (μ₁) will be half of the original viscosity (μ).
μ₁ = (μ/2)
The new pressure drop (ΔP₁) is then
ΔP₁ = Kμ₁ = K(μ/2)
Recall,
K = (ΔP/μ)
ΔP₁ = K(μ/2) = (ΔP/μ) × (μ/2) = (ΔP/2)
Hence, the pressure drop across the pipe also reduces by half of its initial value if the viscosity of the fluid reduces by half of its value.
Hope this Helps!!!
A wood pole with a diameter of 10 in. has a moisture content of 5%. The fiber saturation point (FSP) for this wood is 30%. The wood shrinks or swells 1% (relative to the green dimensions) in the radial direction for every 5% change in moisture content below FSP. a. What would be the percent change in the wood's diameter if the wood's moisture is increased to 55%? b. Would the wood swell or shrink? c. What would be the new diameter?
Answer:
a) Δd(change in wood diameter) = 5%
b) The wood would swell since the moisture content is increasing which will also led to increase in the wood's diameter
C) new diameter (D2) = 10.5 in
Explanation:
Wood pole diameter = 10 inches
moisture content = 5%
FSP = 30%
A) The percentage change in the wood's diameter
note : moisture fluctuations from 5% to 30% causes dimensional changes in the wood but above 30% up to 55% causes no change. hence this formula can be used to calculate percentage change in the wood's diameter
Δd/d = 1/5(30 - 5)
Δd/d = 5%
Δd = 5%
B) would the wood swell or shrink
The wood would swell since the moisture content is increasing which will also led to increase in the wood's diameter
C) The new diameter of the wood
D2 = D + D( [tex]\frac{M1}{100}[/tex] )
D = initial diameter= 10 in , M1 = initial moisture content = 5%
therefore D2 = 10 + 10( 5/100 )
new diameter (D2) = 10.5 in
The change in the diameter of the wood would be 5%
the new diameter would be 10.5 inches
Wood pole diameter = 10 inches
Moisture content = 5%
Fiber saturation point = 30 %
The change in diameter would be[tex]\frac{1}{5} (30-5)[/tex]
= 25/5
= 5%
The percentage change in the diameter of the wood would be 5%
b. This wood is going to rise up instead of shrinking. This is due to the fact that the moisture content that it has has gone up by 55%
c. The new diameter that this wood would have
diameter = 10
moisture = 5%
D = D+D(m)
= 10 + 10(5%)
= 10.5 inches
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There is one reservoir filled with water and also connected with one pipe of uniform cross-sectional diameter. Total head at section 1 is 27 m. At section 2, potential head is 3 m, gage pressure is 160 kPa, vvelocity is 4.5 m/s. Find the major head loss at section 2 in unit of m. Round to the nearest one decimal place.
Answer:
6.7 m
Explanation:
Total head at section 1 = 27 m
at section 2;
potential head = 3 m
gauge pressure P = 160 kPa = 160000 Pa
pressure head is gotten as
[tex]Ph =\frac{P}{pg}[/tex]
where p = density of water = 1000 kg/m^3
g = acceleration due to gravity = 9.81 m/^2
[tex]Ph =\frac{160000}{1000 * 9.81} = 16.309 m[/tex]
velocity = 4.5 m/s
velocity head Vh is gotten as
[tex]Vh = \frac{v^{2} }{2g}[/tex]
[tex]Vh = \frac{4.5^{2} }{2*9.81} = 1.03 m[/tex]
obeying Bernoulli's equation,
The total head in section 1 must be equal to the total head in section 2
The total head in section 2 = (potential head) + (velocity head) + (pressure head) + losses(L)
Equating sections 1 and 2, we have
27 = 3 + 1.03 + 16.309 + L
27 = 20.339 + L
L = 27 - 20.339
L = 6.661 ≅ 6.7 m
(a) A duct for an air conditioning system has a rectangular cross section of 1.8 ft × 8 in. The duct is fabricated from galvanized iron. Determine the Reynolds number for a flow rate of air of 5400 cfm at 100 °F and atmospheric pressure (g=0.0709 lbf/ft3 u=1.8×10-4ft2/s and m=3.96×10-7lbf.s/ft2) (9 points)
Answer:
Reynolds number = 654350.92
Explanation:
Given data:
Cross section of rectangular cross section = 1.8ft * 8 in ( 8 in = 2/3 ft )
Flow rate of air = 5400 cfm = 90 ft^3 / sec
v ( kinematic viscosity of air ) = 1.8*10^-4 ft^2/s
Reynolds number
Re = VDn / v
Dn ( hydraulic diameter ) = 4A / P
where A = area, P = perimeter
a = 1.8 ft ( length )
b = 2/3 ft ( width )
hence Dn = [tex]\frac{4(ab)}{2(a+b)}[/tex] = [tex]\frac{4(1.8*0.6667}{2(1.8+0.6667)}[/tex] = 0.9729 ft
V ( velocity of air flow ) = [tex]\frac{Q}{\pi /4 * Dn^2 }[/tex] = [tex]\frac{90}{\pi /4 * 0.9729^2 }[/tex] = 121.064 ft/sec
back to Reynolds equation
Re = VDn / v -------------- equation 1
V = 121.064 ft/sec
Dn = 0.9729 ft
v = 1.8*10^-4 ft^2/s
insert the given values into equation 1
Re = (121.064 * 0.9729 ) / 1.8*10^-4
= 654350.92
A piston cylinder device contains 5 kg of Refrigerant 134a at 600 kPa and 80 C. The refrigerant is now cooled at constant pressure until it reaches a liquid-vapor mixture state with a quality of 0.3. How much heat was extracted in the process?
Answer:
The answer is 920 kJ
Explanation:
Solution
Given that:
Mass = 5kg
Pressure = 600 kPa
Temperature = 80° C
Liquid vapor mixture state (quality) = 0.3
Now we find out the amount of heat extracted in the process
Thus
Properties of RI34a at:
P₁ = 600 kPa
T₁ = 80° C
h₁ = 320 kJ/kg
So,
P₁ = P₂ = 600 kPa
X₂ =0.3
h₂ = 136 kJ/kg
Now
The heat removed Q = m(h₁ -h₂)
Q = 5 (320 - 136)
Q= 5 (184)
Q = 920 kJ
Therefore the amount of heat extracted in the process is 920 kJ
With 10,000 per day who would be the apparent low bidder; Bidder A was $500,000 and estimated completion date of 200 days. Bidder B was $540,000 and a completion day and estimated completion date of 180.
1. Bidder B
2. Bidder A
Answer:
Bidder B is the lower bidder. the option (A) is correct
Explanation:
Solution
Given that:
Bidder A = $500,000
The estimate completion time = 200 days
Bidder B = $540,000
The estimate completion time =180 days
Overhead charges = $10,000/day
Now,
The Total Bid of A (including overhead charges) = 500,000 + 200 * 10000
= 500,000 +2000000
=$2,500,000
The Total Bid for B (Including overhead charges) = 540,000 + 180 * 10000
=540,000 +1,800,000
=$2340000
Hence Bidder B is apparently a low bidder, since the Total Bid of B is lower than the Total Bid of A.
If a sky diver decides to jump off a jet in Arkansas
with the intention of floating through Tennessee to
North Carolina, then completing his journey in a
likely manner back to Arkansas by drifting North
from his last point. What state would be the third t
be drifted over and what is the estimated distance
between the zone and then drop point?
Answer:
The answer to this question can be defined as follows:
Explanation:
The sky driver began his sky journey from Arkansas, drove across the Tennessee River then landed in North Carolina. He returned to both the north in the very same direction. He began with NC, traveled through Tennessee, eventually lands in Arkansas. But North Carolina has been in the third state on which skydiver was traveling over, and It's also more than 700 miles from Arkansas to the NC.