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3 years ago

9

The thermal efficiency of two reversible power cycles operating between the same thermal reservoirs will a)- depend on the mecha

nisms being used b)- be equal regardless of the mechanisms being used c)- be less than the efficiency of an irreversible power cycle

1 answer:

mestny [16]3 years ago

4 0

C ,, i’m pretty sure .

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The electron concentration in silicon at T = 300 K is given by

puteri [66]

Answer:

$E=1.44*10^-7-2.6exp(\frac{-x}{18} )v/m$

Explanation:

From the question we are told that:

Temperature of silicon $T=300k$

Electron concentration $n(x)=10^{16}\exp (\frac{-x}{18})$

$\frac{dn}{dx}=(10^{16} *(\frac{-1}{16})\exp\frac{-x}{16})$

Electron diffusion coefficient is $Dn = 25cm^2/s \approx 2.5*10^{-3}$

Electron mobility is $\mu n = 960 cm^2/V-s \approx0.096m/V$

Electron current density $Jn = -40 A/cm^2 \approx -40*10^{4}A/m^2$

Generally the equation for the semiconductor is mathematically given by

$Jn=qb_n\frac{dn}{dx}+nq \mu E$

Therefore

$-40*10^{4}=1.6*10^{-19} *(2.5*10^{-3})*(10^{16} *(\frac{-1}{16})\exp\frac{-x}{16})+(10^{16}\exp (\frac{-x}{18}))*1.6*10^{-19}*0.096* E$

$E=\frac{-2.5*10^-^7 exp(\frac{-x}{18})+40*10^{4}}{1.536*10^-4exp(\frac{-x}{18} )}$

$E=1.44*10^-7-2.6exp(\frac{-x}{18} )v/m$

7 0

2 years ago

Ti-6Al-4V has a fracture toughness of 74.6 MPa-m0.5. How much stress (in MPa) would it take to fail a plate loaded in tension th

Nikitich [7]

Answer:

critical stress = 595 MPa

Explanation:

given data

fracture toughness = 74.6 MPa- $\sqrt{m}$

crack length = 10 mm

f = 1

solution

we know crack length = 10 mm

and crack length = 2a as given in figure attach

so 2a = 10

a = 5 mm

and now we get here with the help of plane strain condition , critical stress is express as

critical stress = $\frac{k}{f\sqrt{\pi a}}$ ......................1

put here value and we get

critical stress = $\frac{74.6}{1\sqrt{\pi 5\times 10^{-3}}}$

critical stress = 595 MPa

so here stress is change by plane strain condition because when plate become thinner than condition change by plane strain to plain stress.

plain stress condition occur in thin body where stress through thickness not vary by the thinner section.

6 0

3 years ago

Given frequency, what is the formula for the period of a wave?

Veronika [31]

Answer:

f = c / λ = wave speed c (m/s) / wavelength λ (m). The formula for time is: T (period) = 1 / f (frequency). λ = c / f = wave speed c (m/s) / frequency f (Hz). The unit hertz (Hz) was once called cps = cycles per second.

Explanation:

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2 years ago

The dot plot shows the number of cupcakes bought by each person who came to a bake sale.

Maslowich

The true statement about the dot plot is 1 has 4 and 0 dots.

Explanation:

after creating a Bar chart 4 is the right answer.
The highest among st all the other plots is 1 but 4 shows 3.
Taking an average from all the data points 3 comes to the right answer.
Median the central Mid-point is 3.
Mode also comes to 3.
It is skewed on the right due to the 1st one.
Skewed shows the data point either increasing or in decreasing.
There a to Bi- histograms which has two ups and downs.
The true statement has to be as Mean=Median=Mode is 3.

6 0

3 years ago

Suppose the country of Bangladesh wants a low interest loan to invest in the building of infrastructure. Which international org

musickatia [10]

Answer:

C. UNDP or World Bank.

Explanation:

Suppose the country of Bangladesh wants a low interest loan to invest in the building of infrastructure. The international organizations which Bangladesh would most likely turn to are UNDP or World Bank.

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3 years ago