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3 years ago

1. You are asked to write a report about one of the structures that Transportation Engineers

Engineering

1 answer:

aksik [14]3 years ago

8 0

Answer:

ddition, please state if transportation engineers are involved with any other ... Please specify their specific roles and contributions in the execution of the ...

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The diffusion coefficients for species A in metal B are given at two temperatures:

Kruka [31]

Answer:

a) 149 kJ/mol, b) 6.11*10^-11 m^2/s ,c) 2.76*10^-16 m^2/s

Explanation:

Diffusion is governed by Arrhenius equation

$D = D_0e^{\frac{-Q_d}{RT} }$

I will be using R in the equation instead of k_b as the problem asks for molar activation energy

I will be using

$R = 8.314\ J/mol*K$

and

°C + 273 = K

here, adjust your precision as neccessary

Since we got 2 difusion coefficients at 2 temperatures alredy, we can simply turn these into 2 linear equations to solve for a) and b) simply by taking logarithm

So:

$ln(6.69*10^{-17})=ln(D_0) -\frac{Q_d}{R*(1030+273)}$

and

$ln(6.56*10^{-16}) = ln(D_0) -\frac{Q_d}{R*(1290+273)}$

You might notice that these equations have the form of

$d=y-ax$

You can solve this equation system easily using calculator, and you will eventually get

$D_0 =6.11*10^{-11}\ m^2/s\\ Q_d=1.49 *10^3\ J/mol$

After you got those 2 parameters, the rest is easy, you can just plug them all including the given temperature of 1180°C into the Arrhenius equation

$6.11*10^{-11}e^{\frac{149\ 000}{8.143*(1180+273)}$

And you should get D = 2.76*10^-16 m^/s as an answer for c)

5 0

3 years ago

Steam enters a turbine at 120 bar, 508oC. At the exit, the pressure and quality are 50 kPa and 0.912, respectively. Determine th

Archy [21]

Answer:

The turbine produces <u>955.53 KW</u> power.

Explanation:

Taking the turbine as a system. Applying Law of Conservation of Energy:

m(h₁ - h₂) - Heat Loss = P

where,

m = mass flow rate of steam = 1.31 kg/s

h₁ = enthalpy at state 1 (120 bar and 508°C)

h₂ = enthalpy at state 2 (50 KPa and x = 0.912)

Heat Loss = 225 KW

P = Power generated by turbine = ?

First, we find h₁ from super steam tables:

At,

T = 508°C

P = 120 bar = 12000 KPa = 12 MPa

we find that steam is in super-heated state with enthalpy:

Due to unavailibility of values in chart we approximate the state to 500° C and 12.5 MPa:

h₁ = 3343.6 KJ/kg

Now, for state 2, we have:

P = 50 KPa and x = 0.912

From saturated steam table:

h₂ = hf₂ + x(hfg₂) = 340.54 KJ/kg + (0.912)(2304.7 KJ/kg)

h₂ = 2442.4 KJ/kg

Now, using values in the conservation equation:

(1.31 kg/s)(3343.6 KJ/kg - 2442.4 KJ/kg) - 225 KW = P

5 0

3 years ago

A teacher tells her students, "When you do your math homework assignments, you must use white lined paper. Please, no tear-o

Sindrei [870]

Answer:

The white lined paper

Explanation:

The teacher is most likely putting the while line paper in jeopardy because of the detail process involved in taking care of the paper prior to the submission of the home work.

The fact that a mistake must not be visible due to the instruction of every erasures being thorough and clean. this can cause jeopardy to the paper.

8 0

3 years ago

Tech a says the higher the numarical gear ratio (4:1), the more torque that will be applied to the wheels. Tech b says that the

Zepler [3.9K]

Answer:

Tech A

Explanation:

The amount of energy required to apply the same force with a 1:1 ratio is divided into 4, so you can apply 4 times as much force than a 1:1 ratio. efficiency and speed come into play here, but assuming the machine powering the gear can run at a unlimited RPM, 4:1 will have more force and a slower output speed than a 2:1 ratio.

3 0

3 years ago

Read 2 more answers

Water flows through a horizontal plastic pipe with a diameter of 0.15 m at a velocity of 15 cm/s. Determine the pressure drop pe

Sonja [21]

Answer:0.1898 Pa/m

Explanation:

Given data

Diameter of Pipe $\left ( D\right )=0.15m$