A hollow steel shaft with and outside diameter of (do)-420 mm and an inside diameter of (di) 350 mm is subjected to a torque of 300 KNm, as shown. The modulus of rigidity G for the steel is 80 GPa. Determine: (a) The maximum shearing stress in the shaft. (b) The shearing stress on a traverse cross section at the inside surface of the shaft (c) The magnitude of the angle of twist for a (L) -2.5 m length.

Answers

Answer 1

Answer:

a.  [tex]\tau=51.55 MPa[/tex]

b.[tex]\tau=42.95MPa[/tex]

c.[tex]\theta=7.67\times 10^{-3}[/tex] rad.

Explanation:

Given: [tex]D_i=350 mm,D_o=420 mm,T=300 KN-m ,G=80 G Pa [/tex]

We know that

[tex]\dfrac{\tau}{J}=\dfrac{T}{r}=\dfrac{G\theta}{L}[/tex]

J for hollow shaft [tex]J=\dfrac{\pi (D_o^4-D_i^4)}{64}[/tex]

(a)

 Maximum shear stress [tex]\tau =\dfrac{16T}{\pi Do^3(1-K^4)}[/tex]

      [tex]K=\dfrac{D_i}{D_o}[/tex]⇒K=0.83

[tex]\tau =\dfrac{16\times 300\times 1000}{\pi\times 0.42^3(1-.88^4)}[/tex]

   [tex]\tau=51.55 MPa[/tex]

(b)

We know that [tex]\tau \alpha r[/tex]

So [tex]\dfrac{\tau_{max}}{\tau}=\dfrac{R_o}{r}[/tex]

[tex]\dfrac{51.55}{\tau}=\dfrac{210}{175}[/tex]

[tex]\tau=42.95MPa[/tex]

(c)

[tex]\dfrac{\tau_{max}}{R_{max}}=\dfrac{G\theta }{L}[/tex]

[tex]\dfrac{51.55}{210}=\dfrac{80\times 10^3\theta }{2500}[/tex]

[tex]\theta=7.67\times 10^{-3}[/tex] rad.


Related Questions

A long homogeneous resistance wire of radius ro = 5 mm is being used to heat the air in a room by the passage of electric current. Heat is generated in the wire uniformly at a rate of g=5'107 W/m as a result of resistance heating. If the temperature of the outer surface of the wire remains at 180°C, determine the temperature at r = 2 mm after steady operation conditions are reached. Take the thermal conductivity of the wire to be k = 8 W/m x °C.

Answers

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

Determine the work done by an engine shaft rotating at 2500 rpm delivering an output torque of 4.5 N.m over a period of 30 seconds.

Answers

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

Convection is a function of temperature to the fourth power. a)-True b)-False

Answers

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]

Convert 30.12345 degrees into degrees, minutes and seconds.

Answers

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''

It is true about polymers: a)-They are light-weight materials b)-There are three general classes: thermosets, thermoplastics and thermoset c)-They present long term instability under load d)-All the above

Answers

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.

In a photonic material, signal transmission occurs by which of the following? a)- Electrons b)- Photons

Answers

B. Photons.

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

If you add 10 J of heat to a system so that the final temperature of the system is 200K, what is the change in entropy of the system? a)-0.05 J/K b)-0.30 J/k c)-1 J/K d)-9 J/K e)-2000 J/K

Answers

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

A pipe which is on a slope, transports water downwards. A doubling of cross sectional area takes place 6 above the reference level. The pressure in the smaller pipe, just before the enlargement, is 860 kPa. The flow velocity in the large pipe is 2,4 m/s. Determine the pressure in kPa at a point 1,5 m above the reference level. Ignore friction losses.

Answers

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

A compressed-air drill requires an air supply of 0.25 kg/s at gauge pressure of 650 kPa at the drill. The hose from the air compressor to the drill has a 40 mm diameter and is smooth. The maximum compressor discharge gauge pressure is 690 kPa. Neglect changes in air density and any effects of hose curvature. Air leaves the compressor at 40° C. What is the longest hose that can be used?

Answers

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

Describe the slip mechanism that enables a metal to be plastically deformed without fracture.

Answers

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

SLIPTWINNING

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

A metal rod, 20 mm diameter, is tested in tension (force applied axially). The total extension over a length of 80 mm is 3.04 x 102 mm for a pull of 25 kN. Calculate the normal stress, normal strain and modulus of elasticity (Young's modulus), assuming the rod is linear elastic over the load range.

Answers

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

A strip ofmetal is originally 1.2m long. Itis stretched in three steps: first to a length of 1.6m, then to 2.2 m, and finally to 2.5 m. Compute the true strain after each step, and the true strain for the entire process (i.e. for stretching from 1.2 m to 2.5 m).

Answers

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]

Refectories are one of the types of ceramics that have low melting temperature. a)-True b)-False

Answers

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.

What is the thermal efficiency of this reheat cycle in terms of enthalpies?

Answers

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]

Describe how the Rotary Engine works.

Answers

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:

Radiation heat transfer occurs from any object that is above 0K. a) True b) False

Answers

Answer:

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

What different between 'flow analysis using control volume method' and 'flow analysis using differential method'?

Answers

Answer:

control volume

control volume is used to determine the flow characteristics of  complex shape like turbine and compressors

differential approach

it is carried out by considering infintely small region for fluid analysis.

Explanation:

control volume:

control volume is used to determine the flow characteristics of  complex shape like turbine and compressorsit is used to determine the flow velocity within in the boundaries of control volume. it can also used for force analysis for flow. one main disadvantage of control volume is that it doesn't provide detail information about stress and pressure variation.

differential approach:

it is carried out by considering infintely small region for fluid analysis.solution of the fluid analysis is in the form of differential equationit provide detail information about the flow.

In a vapour absorption refrigeration system, the compressor of the vapour compression system is replaced by a a)- absorber, generator and liquid pump. b)-absorber and generator. c)- liquid pump. d)-generator.

Answers

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.

In a flow over a flat plate, the Stanton number is 0.005: What is the approximate friction factor for this flow a)- 0.01 b)- 0.02 c)- 0.001 d)- 0.1

Answers

Answer:

(a) .01

Explanation:

stanton number is a dimensionless quantity stanton is expressed as [tex]\frac{heat transer}{thermal capacity}[/tex]stanton number is discovered by Thomas edward stanton

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

Which of the following is a correct formula of Ohm s Law (a) E= R/I (b) E=1+R (c)E=I/R (d) E= IR

Answers

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.

What is (a) body forces (b) surface forces?

Answers

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.              

Which of the following is/are FALSE about refining aluminum from the ore state (mark all that apply) a)- A blast furnace is used b)-The ore is called bauxite c)-The process uses a lot of electricity d)-Coke is used to produce the heat

Answers

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.

Calculate the change of entropy of 2 kg of air when its temperature increases from 400 K to 500 K at constant pressure equal to 300 kPa.

Answers

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

                       

Shear strain can be expressed in units of either degrees or radians. a)True b)- False

Answers

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.

A solar panel measures 80 cm by 50 cm. In direct sunlight, the panel delivers 4.8 A at 15 V. If the intensity of sunlight is 1 000 W/m2, what is the efficiency of the solar panel in converting solar energy into electrical energy?

Answers

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]

Briefly describe the function of the thermostatic expansion valve in a vapour compression refrigeration system

Answers

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.      

Saturated water vapor at 140°C is compressed in a reversible, steady-flow device to 895 kPa while its specific volume remains constant. Determine the work required.

Answers

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  

The product second moment of area Ixy is found by multiplying Ix and Iy. a)True b)- False

Answers

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] .

The velocity of flow over a flat plate is doubled. Assuming the flow remains laminar over the entire plate, what is the ratio of the new thermal boundary layer thickness to the original boundary layer thickness?

Answers

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]

A typical aircraft fuselage structure would be capable of carrying torsion moment. a)True b)- False

Answers

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

Other Questions
Which parts of your body have the highest density of touch receptors? What benefis may be derived from that fact? Price ceilings and price floors: a)shift demand and supply curves and therefore have no effect upon the rationing function of prices. b)interfere with the rationing function of prices. c)make the rationing function of free markets more efficient. d)cause surpluses and shortages, respectively. 4. A company found that its monthly profit, P, isgiven by P = -10x2 + 120x - 150 where x is theselling price for each unit of the product.Which of the following is the best estimate ofthe maximum price per unit that the companycan charge without losing money?A $300C$11B $210D $6 Draw the Lewis Dot structure for the following diprotic acid: HOOC-(CH2)4-COOH. 35.50 mL of this acid is titrated to end point with 27.10 mL of 0.970 M KOH. Write the balanced chemical equation for this reaction and determine the unknown concentration of the acid. A 52.5-turn circular coil of radius 5.35 cm can be oriented in any direction in a uniform magnetic field having a magnitude of 0.455 T. If the coil carries a current of 25.3 mA, find the magnitude of the maximum possible torque exerted on the coil. Mr. Franzen is a high school physics teacher. He supports the development of his students' problem-solving skills by providing consistent, encouraging feedback on their assignments. In Bandura's terms, Mr. Franzen is trying to develop his pupils' self-:(A) expetancy(B) esteem(C) efficancy(D) Concept Which pairs of triangles appear to be congruent? Check all that apply. Max (mass = 15 kg) is hanging from one end of a 13-m long bungee cord that has its other end fixed to a bridge above. The bungee cord has a circular cross section with a diameter of 2.5 cm, and a Youngs modulus of 17 MPa. What is the stress in the bungee cord due to Maxs weight? When a 0.15 kg baseball is hit, its velocity changes from +17 m/s to -17 m/s.(a) What is the magnitude of the impulse delivered by the bat to the ball?Ns(b) If the baseball is in contact with the bat for 1.5 ms, what is the magnitude of the average force exerted by the bat on the ball? The point (0,0) is a solution to which of these inequalities?OOOOA. y - 4 Question 14(Multiple Choice Worth 1 points) (07.06 MC) An unknown number x is at most 30. Which graph best represents all the values of x? Number line graph with closed circle on 30 and shading to the right. Number line graph with closed circle on 30 and shading to the left. Number line graph with open circle on 30 and shading to the left. Number line graph with open circle on 30 and shading to the right Write as percents 1) 3/52)7/83)4/254)27/50Write as fractions1)50%2)34%3)56%4)33 1/3% Which of the following is true of Levina Bening Teerlinc? a. She was the highest paid artist in Henry VIIIs court. b. She was involved in Queen Elizabeths court. c. She was one of Henry VIIIs wives. d. A and B are true. On July 9, you purchased 600 shares of Blue Water stock for $32 a share. On August 4, you sold 100 shares of this stock for $33 a share. You sold an additional 100 shares on August 14 at a price of $34.50 a share. The company declared a dividend of $.76 per share on August 3 to holders of record as of Monday, August 17. This dividend is payable on September 15. How much dividend income will you receive on September 15? a.$304 b.$418 c.$380 d.$360 e.$456 Which of these is part of a good dental hygiene? Which of the following methods can be used to obtain sodium chloride from a solid mixture containing sodium chloride and ammonium chloride?A. heatingB. adding water and filteringC. adding sodium hydroxide solution and filteringD. adding silver nitrate solution and filtering The principal function of structure X (Large Intestine) is toA) produce salivary enzymes B) secrete sex hormonesC) absorb waterDidigest ble Most animals and plants reproduce sexually. This means that DNA is passed down to new organisms from two parental organisms. Which of the following is a key advantage of sexual reproduction? A. The elimination of genetic mutations from a parent organism B. Increased genetic diversity for changing environments C. The receipt of the strongest genes from both parents for survival D. The creation of new genes to improve surviva Suppose the gravitational acceleration on a certain planet is only 4.0 m/s2. A space explorer standing on this planet throws a ball straight upward with an initial velocity of 24 m/s. Assume that upward direction is positive. What is the velocity of the ball 3 seconds after it is thrown? What coefficients balance the equation: NH3 + H2O + NH4OHPLEASE HELP