Answer:
a) [tex]h_L=1.17m[/tex]
b)[tex]h_L=1.52m[/tex]
c)[tex]P_1=1.721 kN[/tex]
[tex]P_2=2.236 kN[/tex]
Explanation:
velocities of the pipe;
velocity of small dia pipe
[tex]v_{small}=\frac{Q}{A_{small}} =\frac{0.15}{\frac{\pi}{4}\times d^2 }= \frac{0.15}{\frac{\pi}{4}\times 0.15^2 }=8.52m/s[/tex]
velocity of larger dia pipe
[tex]v_{large}=\frac{Q}{A_{large}} =\frac{0.15}{\frac{\pi}{4}\times d^2 }= \frac{0.15}{\frac{\pi}{4}\times 0.25^2 }=3.05m/s[/tex]
a) pressure head loss when water is flowing from large to smaller pipe
[tex]h_L=(\frac{1}{C_c} -1)^2 \times \frac{v^2}{2g}[/tex]
[tex]h_L=(\frac{1}{0.64} -1)^2 \times \frac{8.52^2}{2\times 9.81} = 1.17m[/tex]
b) pressure head loss when water flow from small pipe to large pipe
[tex]h_L= \frac{v^2}{2g}(1-\frac{A_{small}}{A_{large}} )^2[/tex]
[tex]h_L=\frac{8.52^2}{2\times9.81}(1-\frac{\frac{\pi}{4}\times 0.15^2}{\frac{\pi}{4}\times 0.25^2}} )^2= 1.52 m[/tex]
c) power loss in both cases are
[tex]P_1= \rho g Q h_{L1}= 1000 \times 9.81\times 0.15\times 1.17= 1.721 kN[/tex]
[tex]P_2= \rho g Q h_{L2}= 1000 \times 9.81\times 0.15\times 1.52= 2.236 kN[/tex]
(true/false) Moment thickness, is an index that is proportional to an increment in momentum flow due to the presence of the boundary layer. if false explain why?
Answer:
True
Explanation:
Moment thickness, is an index that is proportional to an increment in momentum flow due to the presence of the boundary layer.
What is hot tear in casting? How can we avoid it?
Answer:
Hot tear casting is the discontinuity or failures occurs during cooling or solidification phase in casting process. It is also known as hot crack
Explanation:
In case when the casting is of weak metal, when it is hot and casted, during the process residual stresses cause failures or discontinuity in casting as it cools resulting in hot tears i,e., material casted is partly liquid and partly solid.
Preventive measures:
Ensure proper mold designA no. of gates should be used to even out temperature gradient. Over heated mold parts should not be usedProper choice of mold materialsOxygen enters an insulated 14.2-cm-diameter pipe with a velocity of 60 m/s. At the pipe entrance, the oxygen is at 240 kPa and 20°C; and, at the exit, it is at 200 kPa and 18°C Calculate the rate at which entropy is generated in the pipe.
Answer:
Entropy generation==0.12 KW/K
Explanation:
[tex]s_2-s_1=C_p\ln \frac{T_2}{T_1}-R\ln \frac{P_2}{P_1}[/tex]
[tex]s_2-s_1=0.891\ln \frac{291}{293}-0.2598\ln \frac{200}{240}[/tex]
[tex]s_2-s_1=0.0412\frac{KJ}{kg-K}[/tex]
Mass flow rate= [tex]\rho\times\dfrac{\pi}{4}d^2V[/tex]
[tex]\rho_1=\dfrac {P_1}{RT_1}[/tex]
[tex]\rho_1=\dfrac {240}{0.2598\times 293}[/tex]
[tex]\rho_1=3.51\frac{kg}{m^3}[/tex]
mass flow rate=[tex]\rho_1A_1V_1[/tex]
So by putting the values
Mass flow rate=2.97 kg/s
So entropy generation=(2.97)(0.0412)
=0.12 KW/K
A Carnot engine whose low-temperature reservoir is at 19.1°C has an efficiency of 30.7%. By how much should the Celsius temperature of the high-temperature reservoir be increased to increase the efficiency to 52.0%?
Answer:
The temperature of the high-temperature source must increase in 12.23ºC.
Explanation:
For a Carnot engine, the efficiency is defined as:
[tex]n = 1- T2/T1 [/tex]
Where T2 and T1 are the low and the high-temperature sources respectively. Therefore for the value of T2 of 19.1ºC and the n equal to 30.7% (0.307), the T1 Temperature can be calculated as:
[tex]n = T1/T1 - T2/T1[/tex]
[tex]n = (T1-T2)/T1[/tex]
[tex]T1.n = (T1-T2)[/tex]
[tex] T1-T1.n =T2[\tex]
[tex] T1(1-n) =T2[/tex]
[tex] T1 =T2/(1-n)[/tex]
[tex] T1 = 19.1\ºC /(1-0.307)[/tex]
[tex] T1 = 27.56\ºC[/tex]
Then for the new effciencie n' of 52% (0.52) the new temeperature T1' will be:
[tex] T1' =T2/(1-n')[/tex]
[tex] T1' = 19.1\ºC /(1-0.52[/tex]
[tex] T1' = 39.79\º C[/tex]
Finally the increment of temperature is:
[tex] AT1 =T1'-T1[/tex]
[tex] AT1 =39.79\º C-27.56\º C[/tex]
[tex] AT1 =12.23\º C[/tex]
[tex] AT1 =12.23\º C[/tex]
Silicon is an intrinsic semiconductor. Adding a small amount of phosphorus provides extra electrons. As a resuit, phosphorus is an p-type dopant. (True , False )
It's an n-type dopants, as it makes the silicone n-type after the doping. so, False
At the mid-plane of a plate in pure bending the stresses are minimum. a)True b)- False
Answer:
I'm pretty sure its true
Explanation:
Why factor of safety is more than 2 in the gears ? What does effect ?
Answer:
explained
Explanation:
Gear is a mechanical components designed for transfer of torque or power from one shaft to the other. Gear designing is a costly affair. The configuration and geometry of gears are such that its designing is tedious task. A lot of precision is required to design a gear. This is why factor of safety of gears are always kept higher.
The higher factor of safety accounts for durability of gears. Gears once made can used for about 200 hundred years. The wear and tear are less and the failure of gears is avoided. And hence whole machine failure can be avoided.
Not a characteristic property of ceramic material (a) high temperature stability (b) high mechanical strength (c) low elongation (d) low hardness
Low hardness is not a characteristic property of ceramic material.
Answer: Option D
Explanation:
One of the most important properties of ceramic material is the hardness that the material displays. The hardness owes to the joining of brittle fracture and plastic flow that makes the material to defend against penetration.
The hardness can be tested with the Vickers test. The hardness of ceramic makes its dominance in the use of construction purpose and manufacture of products. Other general properties are less conductivity, high melting temperature, etc.
Not a characteristic property of ceramic material (d) low hardness.
(a) High temperature stability is a defining feature of ceramics, as they can withstand extreme temperatures without significant degradation.
(b) High mechanical strength is another key characteristic, making ceramics suitable for applications where strength and durability are essential.
(c) Low elongation refers to the minimal deformation under stress, which is typical of ceramics due to their brittle nature.
(d) However, low hardness is not a characteristic property of ceramics. Ceramics are known for their high hardness, making them resistant to wear and abrasion.
A disk brake has two pads which cover 45 degrees of the disk. The outside radius is 6.0 inch and the inside radius is 4.0 inch. Assume a coefficient of friction of 0.4, and a max pressure, pa=100 psi. a) Find the force required to apply one pad. b) Find the torque capacity for both pads.
Answer:
f = 628.32 lb
t = 2513.28 lb-inc
Explanation:
given data:
θ = 45°
outside radius = 6 inch
inside radius = 4 inch
coefficient of friction = 0.4
max pressure = 100 psi
a) determine force required for applying one pad
f = [tex] \frac{\theta }{360}* 2\pi *p_{max}*r_{i}(r_{o}-r_{i})[/tex]
f = [tex] \frac{45 }{360}* 2\pi *100*4(6-4)[/tex]
f = 628.32 lb
b) torque capacity (t)
t = [tex]\mu *f*r_{average}^{}[/tex]
t = 0.4 *628.32*5
torque = 1256.64 lb-inc
for both pad = 2 * 1256.64 =2513.28 lb-inc
Which of the following statements are correct? (a) A substance will emit radiation at a particular wavelength only (b) All substances emit radiation (c) Only some substances emit radiation (d) Bodies black in colour are known as black bodies
Answer: b)All substances emit radiation
Explanation: This is a universal statement that all bodies emit radiations . The radiations are usually in the form of electromagnetic radiations that are being emitted in accordance with temperature that varies from body to body.Even human bodies along with any other body emit radiations These radiations are absorbed by the black body.Therefore the correct option is option(b).
An aluminium alloy used for making cans is cold rolled into a strip of thickness 0.3mm and width 1m. It is coiled round a drum of diameter 15cm, and the outer diameter of the coil is 1m. In the cold rolled condition, the dislocation density is approximately 1015 m-2. Estimate: (i) The mass of aluminium on the coil; (ii) The total length of strip on the coil; (iii) The total length of dislocation in the coiled strip.
Answer:
1. Mass = 2070 kg
2.Total length of strip = 2556 m
3. Total length of dislocation = 7.67 X[tex]10^{14}[/tex] m
Explanation:
Given:
Aluminium coil thickness, t = 0.3 mm
= 0.3 X [tex]10^{-3}[/tex] m
Width of the coil,w = 1 m
Drum diameter, d = 15 cm
= 0.15 m
Coil outer diameter, d = 1 m
Dislocation density = [tex]10^{15}[/tex] [tex]m^{2}[/tex]
1). Area of the coil, A = [tex]\frac{\pi }{4}\times[/tex] ( [tex]d_{coil} ^{2}[/tex]-[tex]d_{drum} ^{2}[/tex])
A = [tex]\frac{\pi }{4}\times (1^{2}-0.15^{2})[/tex]
A = 0.767 [tex]m^{2}[/tex]
Volume of the coil,V = A X w
= 0.767 X 1
= 0.767 [tex]m^{3}[/tex]
We know density of aluminum at STP = 2.7 X [tex]10^{3}[/tex]
Therefore, mass of the aluminum coil is,
Mass,m = Density of aluminium X Volume
= 2.7 X [tex]10^{3}[/tex] X 0.767
= 2070 kg
Mass = 2070 kg
2). Total length of trip of coil is given by
L = Volume of coil / area of strip
= [tex]\frac{0.767}{1\times 0.3\times 10^{-3}}[/tex]
= 2556 m
Total length of strip = 2556 m
3). Total length of dislocation of the coiled strip = volume X dislocation density
= 0.767 X [tex]10^{15}[/tex]
= 7.67 X [tex]10^{14}[/tex]
Total length of dislocation = 7.67 X[tex]10^{14}[/tex] m
Segmented solid rockets require what special component? A. Igniters B. Liners C. O-rings D. Nozzle gimbals
Answer: D) Nozzle gimbals
Explanation: Igniters are present for the ignition power in the segmented solid rocket, liners are the basic requirement in the engine of the rocket,O-rings are also a general part of the segmented solid rocket .So, these are the general purpose parts of the segmented solid rocket but nozzle gimbals are the special units of the rocket as they provide improved thrust in various direction in accordance with the rocket.So, option (d) is the correct option.
Answer:
D. Nozzle gimbals
Explanation:
Segmented solid rockets require the special component, nozzle gimbals.
How to called crystalline lattice changes at the temperature change a) oxidation; b) primary crystallization c) allotropy d) anisotropy.
Answer: (c)Allotropy
Explanation: Allotropy is defined as the feature of the material to exist in different chemical forms or state while being in the same physical state. So, allotropy responsible for maintenance of the crystalline lattices during the temperature changes and does not alter the physical state of it. It helps elements to exist in different forms by modifying the structure of the chemical state.
Glass-ceramic is a fine-grained crystalline ceramic formed by the controlled crystallization of a ceramic. ( True , False )
In this type of projection, the angles between the three axes are different:- A) Isometric B) Axonometric C) Trimetric D) Dimetnic
Answer:
The correct answer is C) Trimetric
Explanation:
The most suitable answer is a trimetric projection because, in this type of projection, we see that the projection of the three angles between the axes are not equal. Therefore, to generate a trimetric projection of an object, it is necessary to have three separate scales.
Convective heal transfer is defined as______
Answer: Convective heat transfer is defined as the transfer of heat from a particular place to another with the help of fluid movements.
Explanation: Convective heat also knows as convection that is transfer of heat from one place to another place by the help of fluid movements around the area having different temperatures. This process has many examples in everyday life to understand the process better.
Ex.- the melting of ice from solid to liquid form as it comes in contact of high temperature as heat surrounds the ice in form of air.
The point where all three phases coexist on a P-T diagram.
Answer:
The point where all three phases coexist on a P-T diagram is called triple point.
Explanation:
A phase diagram of a substance is a graphical representation of the transition of its physical state under various temperature and pressure conditions.
A typical phase diagram usually consists of:
(A) Fusion curve - The curve that shows that the solid and the liquid state in in equilibrium with each other.
(B) Vaporization curve - The curve that shows that the liquid and the gaseous state in in equilibrium with each other.
(C) Sublimation curve - The curve that shows that the solid and the gaseous state in in equilibrium with each other.
(D) Triple point - This is a point in the phase diagram in which all the three state exists in equilibrium.
For example, Considering the phase diagram of water, The triple point occurs at a pressure of 0.6 kPa and 0.01⁰C.
The phase diagram is shown in image below:
Solid rockets can experience significant 2 phase flow. a) True b) False
Answer:
the answer is false solid rockets can experience significant 2 phase flow
What is meant by thermodynamic property? How do you classify the property? Explain with specific examples.
Answer:
The condition of very system can be identified by some physical characteristics of the system known as Thermodynamic Property of the system. For example, pressure, temperature, volume, etc.
Explanation:
Thermodynamic properties are nothing but the physical characteristics of any body by which the physical condition of the body can be described. properties describes the different states of a system. They are macroscopic.
Properties are of two types ---
Intensive property
Extensive property
Intensive Property : Those properties of a system which does not depend upon mass of the system are known Intensive property.
For example, pressure, temperature, density,specific volume, etc
Extensive Property : Properties that depends on the mass oh the system is called Extensive properties.
For example, energy, volume, etc.
Which of the following is least likely to affect the convection heat transfer coefficient? a)- Thermal conductivity of the fluid b)-Geometry of the solid body c)-The roughness of the solid surface d)-Type of fluid motion (laminar or turbulent) e)- Fluid velocity f)- Density of the solid body g)-Dynamic viscosity of the fluid
Answer:
f)Density of the solid body
Explanation:
We know that heat transfer due to convection is given by
Q=hAΔT
Where
A is the area ,which represent the geometry of solid body or surface.
h is the heat transfer coefficient which depends on
1.Thermal conductivity of fluid
2.Motion of fluid
3.Type of fluid flow(Laminar or Turbulent)
4.Viscosity of fluid
5.Surface condition
So from the above parameters ,we can say that heat transfer due to convection does not depends on density of the solid body.
In an air compressor the compression takes place at a constant internal energy and 50KJ of heat are rejected to the cooling water for every Kilogram of air. Calculate the work input for the compression stroke per kilogram of air?
Answer:
work is 50 kj
Explanation:
Given data
heat (Q) = 50 kj
To find out
work input for the compression stroke per kilogram of air
Solution
we will apply here "first law of thermodynamics" i.e.
The First Law of Thermodynamics states that heat is a form of energy, subject to the principle of conservation of energy, that heat energy cannot be created or destroyed. It can be transferred from one location to another location. i.e.
ΔU = Q – W ................1
here ΔU is change in internal energy, Q is heat and W is work done
here U = 0 because air compressor the compression takes place at a constant internal energy in question
so that by equation 1
Q = W
and Q = 50
so work will be 50 kj
What are "primary alpha" and "primary beta"?
At any given state the specific internal energy of a gas is always greater its specific enthalpy. a)True b) False
Answer:
(b)False
Explanation:
We know that specific Internal energy of gas u=[tex]C_v[/tex]T
and specific enthalpy of gas h=[tex]C_p[/tex]T
If we take the case of air we know that
[tex]C_v[/tex]=0.707 KJ/Kg=K , [tex]C_p[/tex]=1.005 KJ/Kg=K
If we take A fixed temperature T=300 K
so u=212.1 KJ/ kg ,h=301.5 KJ/kg
So we can say that specific enthaply of gas is always greater than its specific internal energy.
The speed of sound in air is proportional to the square root of the absolute temperature. If the speed of sound is 349 m/s when the air temperature is 20 °C, what is the temperature of the air when the speed of sound is 340 m/s? Give your answer in °C, K, °F, and R (Rankine).
Given:
Let the speed of sound be represented by 'v' then
v ∝ [tex]\sqrt{T}[/tex] (1)
[tex]v_{1}[/tex] = 349 m/s
[tex]v_{2}[/tex] = 340 m/s
[tex]T_{1}[/tex] = 20°C = 273+20 = 293 K
Formulae used:
1) °C = K + 273
2) K = °C - 273
3) °F = 1.8°C + 32
4) °R = °F + 459.67
Solution:
From eqn (1),
[tex]\frac{v_{1}}{v_{2}} = \sqrt{\frac{T_{1}}{T_{2}}}[/tex]
[tex]T_{2}[/tex] = [tex]T_{2} = (\frac{v_{2}}{v_{1}})^{2}T_{1}[/tex]
[tex]T_{2} = (\frac{340}{349})^{2}{293}[/tex] = 278.08 K
Now, Usinf formula (1), (2), (3) and (4) respectively, we get
1) T = 293 K
2) T = 293 -278.8 = 5.08°C
3) T = 1.8(5.08) + 32=41.14°F
4) T = 41.14 + 459.67 = 500.81°R
A coil of wire 8.6 cm in diameter has 15 turns and carries a current of 2.7 A. The coil is placed in a magnetic field of 0.56 T. What is the magnitude of the maximum torque that can be applied to the coil by the magnetic field?
Answer:
Explanation:
it is given that diameter = 8.6 cm
[tex]radius =\frac{8.6}{2}=4.3\ cm=4.3\times 10^{-2}\ m[/tex]
current =2.7 ampere
number of turns = 15
[tex]area =\pi r^2=3.14\times \left ( 4.3\times 10^{-2} \right )^{2}=0.005806 m^{2}[/tex]
magnetic field =0.56 T
maximum torque= BINASINΘ for maximum torque sinΘ=1
so maximum torque==0.56×2.7×0.005806×15=0.13174 Nm
What is Potential flow?
Answer: Potential flow states about the velocity field considering it as gradient of scalar function such as the velocity potential. It is considered same as irrotational flow.
Explanation:In the study of fluid dynamics , potential flow is stated as the term for describing about the velocity field taking it as the gradient of a scalar function. Therefore, potential flow is stated by an irrotational velocity field and there is a irrotation because of the curl of the gradient of scalar quantity is zero.Potential flow is considered same as the irrotational flow that is the particles in the fluids that do not rotate.
For water the critical temperature is 374 C, water at T- 400 C exist as vapor (____)
Answer:
The statement is False.
Explanation:
Critical temperature is defined as the temperature at and above which the liquid and the gaseous states are indistinguishable. This is the temperature at and above which the liquid cannot be liquefied.
Above critical temperature or pressure, the substance is in supercritical fluid (SCF) state. A supercritical fluid is the one in which liquid and gaseous state can not be distinguished. It can dissolve like liquids and can effuse like solids.
Water above its critical temperature exists in SCF state which is neither vapor nor liquid.
Thus, the statement is false.
Using the saturated table, the specific entropy of of subcooled liquid water at 75 C and 200 kPa is______
Answer Explanation :
We know that entropy is the measure of molecular randomness it is denoted by S It is a thermodynamic property of gas it is an extensive property means its depend on the mass of the the system and specific entropy is defined as the entropy per unit mass its unit is KJ/kg.k
by using standard table the specific entropy for the subcooled liquid is 1.057 KJ/kg.k standard table is used for knowing the specific entropy of different liquid and gaes
Stated as an equation, what is the Clausius Inequality?
Answer:
Clausius inequality is defined as, it applies in the cycle of real engine and there is negative entropy change. When the entropy given in the cycle during the environment is larger than entropy transferred into heat engine from hot reservoir. As, entropy of reversible system are zero.
Clausius Inequality is defined as:
[tex]R_2-R_1> \oint_{T_1}^{T_2}\frac{dQ}{T}[/tex]
Where R1 and R2 are not be equal.
Before cutting coarse screw threads, the operator should lubricate: A. The leadscrew and gearbox B. The ways and cross slide C. The carriage and half-nuts D. A1l of the above
Answer:
(d) all of the above
Explanation:
before cutting the screw threads the operator should lubricate all of the machine parts given in the option that is lead screw and gearbox , the ways and the cross slide and the carriage and half-nuts. we should use lubrication because it reduces the overall system friction and if friction is reduced then heat generated due to friction is also decreases which is beneficial
so option (D) will be correct because we need lubricate in all the given parts