A circular plate with diameter of 20 cm is placed over a fixed bottom plate with a 1 mm gap between two plates filled with Kerosene at 40 degree C, shown in the following figure. Find the torque needed to rotate the top plate at 5 rad/s. The velocity distribution in the gap is linear and the shear stress on the edge of the rotating plate can be neglected.

Answer:

true

Explanation:

shear strain is define as the ratio of change in deformation to the original length perpendicular to the axes of member due to shear stress.

     ε    = deformation/original length

strain is a unit less quantity but shear stain is generally expressed in radians but it can also be expressed in degree.

Answer:

strains for the respective cases are

0.287

0.318

0.127

and for the entire process 0.733

Explanation:

The formula for the true strain is given as:

[tex]\epsilon =\ln \frac{l}{l_{o}}[/tex]

Where

[tex]\epsilon =[/tex] True strain

l= length of the member after deformation

[tex]l_{o} = [/tex] original length of the member

Now for the first case we have

l= 1.6m

[tex]l_{o} = 1.2m[/tex]

thus,

[tex]\epsilon =\ln \frac{1.6}{1.2}[/tex]

[tex]\epsilon =0.287[/tex]

similarly for the second case we have

l= 2.2m

[tex]l_{o} = 1.6m[/tex]   (as the length is changing from 1.6m in this case)

thus,

[tex]\epsilon =\ln \frac{2.2}{1.6}[/tex]

[tex]\epsilon =0.318[/tex]

Now for the third case

l= 2.5m

[tex]l_{o} = 2.2m[/tex]

thus,

[tex]\epsilon =\ln \frac{2.5}{2.2}[/tex]

[tex]\epsilon =0.127[/tex]

Now the true strain for the entire process

l=2.5m

[tex]l_{o} = 1.2m[/tex]

thus,

[tex]\epsilon =\ln \frac{2.5}{1.2}[/tex]

[tex]\epsilon =0.733[/tex]

Answer:

  Rotary engine was early known by the name of internal combustion engine. It convert heat from a high pressure of combustion. The main advantage of rotary engine is that it can be operate with less number of vibration. It works on the principle of converting pressure into rotating motion. In rotary engine the expansion pressure is applied on the flank rotor.  

Answer: The rotary engine works on the same basic principle as the piston engine: combustion in the power plant releases energy to power the vehicle. However, the delivery system in the rotary engine is wholly unique. The piston engine performs four key operations: intake, compression, combustion, and exhaust.

Explanation:

Answer:

The solar panel efficiency in converting solar energy in electrical energy is 18%.

Explanation:

The solar panel's  efficiency can be defined as:

[tex] n= \frac{Pe}{Ps}*100\%[/tex]

Where Pe and Ps are the output electrical power and input solar power respectively. The electrical is computing in terms of the voltage and current delivered:

[tex]Pe=I.V[/tex]

[tex]Pe=4.8 A * 15 V[/tex]

[tex]Pe= 72 AV = 72 W [/tex]

The net solar power of panel is found by multiplying the solar intensity by the panel area in square meters:

[tex]Ps = Is.Ap[/tex]

[tex]Ps = 1000 W/m^2 *(0.8 m * 0.5 m)[/tex]

[tex]Ps = 1000 W/m^2 *(0.40 m^2)[/tex]

[tex]Ps = 400 W [/tex]

Finally the panel efficience n is:

[tex] n= \frac{72 W}{400 W}*100\%[/tex]

[tex] n= 0.18*100\% = 18\%[/tex]

Answer:

A) Body forces-

  Body forces is the forces which acts throughout the volume of the body.     It is basically distributed over the volume and mass of the element of the body. In a body force other body exerts a force without being contract.  

For example : Gravity forces, electromagnetic forces, centrifugal forces.

B) Surface forces-

   Surface forces is the forces which are distributed all over the free surface of the body. Surfaces forces can be further divided into two perpendicular components as: normal forces and shear forces.

For example : Pressure forces and viscous forces.              

Answer:

control volume

differential approach

Explanation:

control volume:

differential approach:

Answer:

L = 46.35 m

Explanation:

GIVEN DATA

\dot m  = 0.25 kg/s

D = 40 mm

P_1 = 690 kPa

P_2 = 650 kPa

T_1 = 40° = 313 K

head loss equation

[tex][\frac{P_1}{\rho} +\alpha \frac{v_1^2}{2} +gz_1] -[\frac{P_2}{\rho} +\alpha \frac{v_2^2}{2} +gz_2] = h_l +h_m[/tex]

where[tex] h_l = \frac{ flv^2}{2D}[/tex]

[tex]h_m minor loss [/tex]

density is constant

[tex]v_1 = v_2[/tex]

head is same so,[tex] z_1 = z_2 [/tex]

curvature is constant so[tex] \alpha = constant[/tex]

neglecting minor losses

[tex]\frac{P_1}{\rho}  -\frac{P_2}{\rho} = \frac{ flv^2}{2D}[/tex]

we know[tex] \dot m[/tex] is given as[tex] = \rho VA[/tex]

[tex]\rho =\frac{P_1}{RT_1}[/tex]

[tex]\rho =\frac{690 *10^3}{287*313} = 7.68 kg/m3[/tex]

therefore

[tex]v = \frac{\dot m}{\rho A}[/tex]

[tex]V =\frac{0.25}{7.68 \frac{\pi}{4} *(40*10^{-3})^2}[/tex]

V = 25.90 m/s

[tex]Re = \frac{\rho VD}{\mu}[/tex]

for T = 40 Degree, [tex]\mu = 1.91*10^{-5}[/tex]

[tex]Re =\frac{7.68*25.90*40*10^{-3}}{1.91*10^{-5}}[/tex]

Re = 4.16*10^5 > 2300 therefore turbulent flow

for Re =4.16*10^5 , f = 0.0134

Therefore

[tex]\frac{P_1}{\rho}  -\frac{P_2}{\rho} = \frac{ flv^2}{2D}[/tex]

[tex]L = \frac{(P_1-P_2) 2D}{\rho f v^2}[/tex]

[tex]L =\frac{(690-650)*`10^3* 2*40*10^{-3}}{7.68*0.0134*25.90^2}[/tex]

L = 46.35 m

Answer:

True, hope this helps but there no school right now its summer

Answer:

0.05 J/K

Explanation:

Given data in question

heat (Q) = 10 J

temperature (T) = 200 K

to find out

the change in entropy of the system

Solution

we will solve this by the entropy change equation

i.e  ΔS = ΔQ/T           ...................1

put the value of heat Q and Temperature T in equation 1

ΔS is the enthalpy change and T is the temperature

so  ΔS = 10/200

ΔS = 0.05 J/K

Answer:

Given:

laminar flow

and since velocity of flow is doubled, we consider [tex]v_{n}[/tex] as new velocity and [tex]v_{o}[/tex] as original velocity

Explanation:

As per laminar flow, thickness, t is given by

t = [tex]\frac{4.91x}{\sqrt( R_{ex}) }[/tex]

t =  [tex]\frac{4.91x}{\sqrt{\frac{\rho vx}{\mu }}}[/tex]

t = [tex]\frac{4.91x\mu }{\sqrt{\rho vx}}[/tex]

where,

[tex]R_{ex}[/tex] = Reynold's no.

therefore,

t ∝ [tex]\frac{1}{\sqrt{v} }[/tex]

Now,

[tex]\frac{t_{n} }{t_{o} }[/tex] = [tex]\sqrt{(\frac{v_{o} }{v_{n} })}[/tex]

[tex]\frac{t_{n} }{t_{o} }[/tex] = [tex]\sqrt{(\frac{v_{o} }{2v_{o} } )} =\frac{1}{\sqrt{2} }[/tex]

therefore,

[tex]t_{n}:t_{o} = 1:\sqrt{2}[/tex]

Answer:

   [tex]\eta =\dfrac{\left (h_3-h_4\right )+(h_5-h_6)-(h_2-h_1)}{(h_3-h_2)+(h_5-h_4)}[/tex]

Explanation:

For close gas turbine:

       Gas turbine works on Brayton cycle.Gas turbine have lots of applications like ,it is use in aircraft,in land applications etc.

Reheating is the method to improve the efficiency of the gas turbine.In reheating gas is expanding in two turbine instead of one turbine alone.Two turbine like high pressure turbine and low pressure turbine are used for expansion.

In the above diagram 1-2 is a compressor,2-3 heat addition,3-4 high pressure turbine,4-5 reheating of cycle 5-6 low pressure turbine,6-1 heat rejection,

We know that    [tex]\eta =\frac{W_{net}}{Q_{s}}[/tex]

Now take [tex]h_{1},h_{2},,h_{3},h_{4},h_{5},h_{6}[/tex] represent the enthalpy of point 1,2,3,4,5,6 in the cycle respectively.

So total heat supplied [tex]Q_S[/tex]=

[tex]\left (h_3-h_2\right )+\left (h_5-h_4\right )[/tex]

Net work out put

[tex]W_{net}[/tex]=[tex]\left (h_5-h_6\right )-\left (h_2-h_1\right )[/tex]

So efficiency   [tex]\eta =\frac{W_{net}}{Q_{s}}[/tex]

      [tex]\eta =\dfrac{\left (h_3-h_4\right )+(h_5-h_6)-(h_2-h_1)}{(h_3-h_2)+(h_5-h_4)}[/tex]

Answer:

T = 212.8125°C

Explanation:

Given

radius of the wire, [tex]r_{0}[/tex] = 5 mm 0.005 m

heat generated, g = 5 x [tex]10^{7}[/tex] W/[tex]m^{3}[/tex]

outer surface temperature, [tex]T_{S}[/tex] = 180°C

Thermal conductivity, k = 8 W / m-k

Now maximum temperature occurs at the center of the wire

that is at r=0,

Therefore, [tex]T_{o}=T_{S}+\frac{g\times r_{o}^{2}}{4\times k}[/tex]

                  [tex]T_{o}=180+\frac{5\times 10^{7}\times 0.005^{2}}{4\times 8}[/tex]

                 [tex]T_{o}=219.0625[/tex]°C

Therefore, temperature at r = 2 mm

[tex]\frac{T-T_{S}}{T_{O}-T_{S}}= 1-\left (\frac{r}{r_{O}}  \right )^{2}[/tex]

[tex]\frac{T-180}{219.0625-180}= 1-\left (\frac{2}{5}  \right )^{2}[/tex]

Therefore, T = 212.8125°C

Answer:

0.45516

Explanation:

ENTROPY : Entropy is a measure of molecular disorder it is denoted by S. Entropy is also measured in terms of thermal energy and temperature it is equal to thermal energy per unit temperature.

from the table S₁=1.99194 KJ/kg.k (at 400k)

from the table S₂=2.21952 KJ/kg.k (at 500k)

so total entropy change is given by =m (S₂-S₁)

=2(2.21952-1.99194)

=0.45516

Answer and explanation:

Deformation means change in position plastic deformation mainly cause due to motion of dislocation

THERE ARE MAINLY TWO MECHANISM BY WHICH PLASTIC DEFORMATION TAKES PLACE

SLIP : slip is a process of sliding of blocks over one  another along the planes  these planes are called slip planes slip takes place when the shear stress exceeds than the critical value of stress distance between the slip planes are called slip lines the resistance for slip plane is very less as compared to any other planes the slip plane is the plane has very high density

Answer: d) All of the above

Explanation: Polymers are the substances that have molecular structure with having same bonds in the entire molecule together.There are light weight substance which occur natural as well as artificially. They are also categorized  as thermoplastics ,thermosets, and elastomers. They also have the property of being stretching and bending under the pressure or load they are also instable. Therefore, all the options are correct statement about polymers.

Answer:

a). absorber, generator and liquid pump

Explanation:

The Vapour absorption system consists of compression, expansion, condensation and evapouration processes. This system uses ammonia, lithium bromide or water as refrigerant.

                  An absorber, pump and generator is used in place of a compressor in the vapour compression refrigeration system. The operation is smooth in vapour absorption system since all the moving elements are in the pump only. This system make use of low energy like heat and can work on lower evapourator pressure. It has low Coefficient of performance.

Answer:

True

Explanation:

An aircraft is subject to 3 primary rotations

1) About longitudinal axis known as rolling

2) About lateral axis known as known as pitching

3) About the vertical axis known as yawing

The rolling of the aircraft induces torsion in the body of the aircraft thus the fuselage structure should be capable of carrying torsion

Answer:

P₂ = 830.75 kPa

Explanation:

Given:

Pressure in the smaller pipe,P₁  = 860 kPa

Velocity in the larger pipe, v₂ = 2.4 m/s

Therefore velocity in the smaller pipe, v₁ = 4.8 m/s ( velocity gets doubled since area is reduced to half )

Height at section where the area is doubled, z₁ = 6 m

Height at the section where pressure is to be calculated, z₂ = 1.5 m

Now apply Bernouli Equation between the section of enlargement and at section where pressure is to be calculated,

[tex]\frac{P_{1}}{\rho .g}+\frac{v_{1}^{2}}{2.g}+z_{1} = \frac{P_{2}}{\rho .g}+\frac{v_{2}^{2}}{2.g}+z_{2}[/tex]

[tex]\frac{860}{1000 \times 9.81}+\frac{4.8^{2}}{2\times 9.81}+6 = \frac{P_{2}}{1000 \times 9.81}+\frac{2.4^{2}}{2\times 9.81}+1.5[/tex]

P₂ = 830.75 kPa

Therefore, pressure at the section 1.5 m above datum is 830.75 kPa

Answer:

The work required to compress the saturated water vapor to 895 kPa pressure is 130.9540 k J/Kg

Explanation:

Given data in question

temperature = 140°C

pressure  (P2) = 895 kPa

To find out

work required for compress saturated water

Solution  

We know the equation for reversible work for compress saturated water vapor

i.e.  

W =  [tex]-\int_{1}^{2}vdP-\Delta ke - \Delta pe[/tex]

w is  reversible work, v is specific volume, P is water vapor pressure and

ke is kinetic energy and pe is potential energy

and in question we have given v is constant so ke and pe will be zero

so  

W =  [tex]-\int_{1}^{2}vdP[/tex]

W =  -v( P2 - P1 )

we can given in question temperature = 140°C and use steam table "A-4 saturated water - temperature table"

at this water property P1 will be 361.53 kPa and v will be 0.50850 m³/kg

so put these value in above equation

W =  -0.50850( 104 - 361.53 )

W = 130.9540 kJ/Kg  

B. Photons.

In a photonic material, signal transmission occurs by photons which are light particles.

Answer:

30.12345° can be written as : 30°7'20.42''

Or,

30 degrees 7 minutes and 20.42 seconds.

Explanation:

1 degree consists of 60 arc minutes.  

1 arc minutes consists of 60 arc seconds.  

Thus, 30.12345° can be written as:

30.12345°= 30° + 0.12345°

1° = 60'

So,

0.12345° = 0.12345*60' = 7.407'

Thus, 7.407' can be written as:

7.407' = 7' + 0.407'

1' = 60''

So,

0.407' = 0.407*60'' = 20.42''

Thus,

30.12345° can be written as : 30°7'20.42''

Answer:

The options a)- A blast furnace is used and d)-Coke is used to produce the heat are FALSE.

Explanation:

Aluminium is a chemical element and the most abundant metal present in the Earth's crust. An aluminium ore is called bauxite. Aluminium is extracted from its ore by the process of electrolysis, called the Hall–Héroult process. The extraction of aluminium is an expensive process as it requires large amount of electricity. The bauxite is purified to produce aluminium oxide. Then, aluminium is extracted from the aluminium oxide.

Therefore, the refining of aluminum from its ore does not involve the use of a blast furnace and coke to produce heat.

Answer:

Explanation:

Thermostatic expansion valve is mainly a throttling device commonly used in air conditioning systems and refrigerators.

It is an automatic valve that maintains proper flow of refrigerant in the evaporator according to  the load inside the evaporator. When the load in the evaporator is higher the valve opens and  allows the increase in flow of refrigerant and when the load reduces the valve closes a bit and  reduces the flow of refrigerant. This process leads to higher efficiency of compressor as well as the whole refrigeration system.  Thus TEV works to reduce the pressure of refrigerant from higher condenser pressure to the lower evaporator pressure. It also keeps the evaporator active.      

Answer:

b). False

Explanation:

A refractory material is a type of material that can withstand high temperatures without loosing its strength. They are used in reactors, furnaces, kilns, etc.

    Refractory materials are certain super alloys and ceramics materials.

Properties of refractory materials :

1. Refractory materials have high melting point.

2.They acts barriers between high heat zone and low heat zone.

3. The specific heat of refractory material is very low.

4. Refractories that have high bulk densities are better in quality.

Hence, Refractory materials have a very high melting temperature.

Answer:

(b)False

Explanation:

[tex]I_{xy}[/tex] defined as

      [tex]I_{xy}[/tex] =[tex]\int \left (x\cdot y\right )dA[/tex]

Where x is the distance from centroidal x-axis

           y is the distance from centroidal y-axis

          dA is the elemental area.

The product of x and y can be positive or negative ,so the value of  [tex]I_{xy}[/tex] can be positive as well as negative .

So from the above expressions we can say that the product of [tex]I_{x},I_y[/tex] is different from [tex]I_{xy}[/tex] .

Answer:

(a) .01

Explanation:

there is relation between friction factor and stanton number and friction factor that is stanton number is half of friction factor

stanton number =[tex]\frac{friction factor}{2}[/tex]

.005=[tex]\frac{friction factor}{2}[/tex]

friction factor =2×.005

friction factor=.01

Answer:

The given statement for temperature and convection is False.

Explanation:

Convection is not a function of temperature to the fourth power but it depends linearly on temperature. the below equation shows the linear relation of heat transfer due to convection and temperature:

Q = [tex]H_{c}A(T_{hot} - T_{cold} )[/tex]

Whereas, radiation is a function of temperature to the fourth power.

The Stefan-Boltzmann law gives the relationship between an object's temperature and the amount of radiation it emits. The law is given by:

[tex]Q=\sigma T^{4}[/tex]

Answer:stress=79.56MPa

strain=[tex]3.8\times 10^{-4}[/tex]

Young Modulus=209.36 GPa

Explanation:

Given data

d=20 mm

Length[tex]\left ( L\right )[/tex]=80mm

[tex]\Delta {L}[/tex]=[tex]3.04\times 10^{-2}[/tex]mm

Load=[tex]25\times 10^{3}[/tex]N

[tex]\left ( i\right )[/tex]

Stress=[tex]\frac{Load\ applied}{cross-section}[/tex]

Stress=[tex]\frac{25\times 10^{3}}{314.2}[/tex]

Stress=79.56MPa

[tex]\left ( ii\right )[/tex]

Strain=[tex]\frac{Change\ in\ length}{Length}[/tex]

Strain=[tex]\frac{3.04\times 10^{-3}}{80}[/tex]

Strain=[tex]3.8\times 10^{-4}[/tex]

[tex]\left ( iii\right )[/tex]

young modulus[tex]\left ( E\right )[/tex]=[tex]\frac{Stress}{Strain}[/tex]

E=[tex]\frac{79.56\times 10^{6}}{3.8\times 10^{-4}}[/tex]

E=209.36GPa

Answer: The correct answer is Option d.

Explanation:

Ohm's law is defined as the law which gives us the relationship between voltage and current.

In electronics, the equation used to represent this law is:

[tex]E=IR[/tex]

where,

E = voltage of the circuit. The unit for this is Volts.

I = current of the circuit. The unit for this is Amperes

R = resistance of the circuit. The unit for this is Ohms.

Hence, the correct answer is Option d.

Answer:

work done= 2.12 kJ

Explanation:

Given

N=2500 rpm

T=4.5 N.m

Period ,t= 30 s

[tex]torque =\frac{power}{2\pi N}[/tex]

[tex]power=2\pi N\times T[/tex]

P=[tex]2\times \pi \times2500 \times 4.5[/tex]

P=70,685W

P=70.685 KW

power=[tex]\frac{work done}{time}[/tex]

work done = power * time

                  = 70.685*30=2120.55J

                  = 2.12 kJ