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3 years ago

11

For an irreversible isothermal process occured in a system with temperature T, which following expression best evaluates the cha

nge of entropy of the isolated system? (A) ∆S=0 (B) ∆S<0 (C) ∆S>0 (D) ∆S=Q/T (E) ∆S>Q/T (F) ∆S

1 answer:

Ulleksa [173]3 years ago

8 0

Answer:

∆S=Q/T

Explanation:

Given the general expression for entropy:

$\Delta S = \int \frac{dQ}{T}$

We can proceed to find the final expression.

As the temperature does not change, it can be removed from the integral, leaving:

$\Delta S=\frac{1}{T} \int dQ$

Now, we proceed to solve the integral to have the final answer:

$\Delta S=\frac{1}{T} Q=\frac{Q}{T} \\\\Therfore\\\\\Delta S=\frac{Q}{T}$

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schepotkina [342]

Answer: 150m

Explanation:

The following can be depicted from the question:

Dimensions of outer walls = 9.7m × 14.7m.

Thickness of the wall = 0.30 m

Therefore, the plinth area of the building will be:

= (9.7 + 0.30/2 + 0.30/2) × (14.7 × 0.30/2 + 0.30/2)

= 10 × 15

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3 years ago

What is the composition, in atom percent, of an alloy that consists of 4.5 wt% Pb and 95.5 wt% Sn?

jeka57 [31]

Answer: Option A is correct -- 2.6 at% Pb and 97.4 at% Sn.

Explanation:

Option A is the only correct option -- 2.6 at% Pb and 97.4 at% Sn. While option B, which is 7.6 at% Pb and 92.4 at% Sn. and option C, which is 97.4 at% Pb and 2.6 at% Sn. and option D, which is 92.4 at% Pb and 7.6 at% Sn. are wrong.

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4 years ago

Why do we need an architect?explain briefly by focusing on its various sectors.

lara [203]

Answer:

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Explanation:

What are the 3 main functions of an architect?

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2 years ago

What is the next measurement after 2' -6" on the architect's scale?

Diano4ka-milaya [45]

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Explanation:

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3 years ago

A 50 mm diameter shaft is subjected to a static axial load of 160 kN. If the yield stress of the material is 350 MPa, the ultima

zvonat [6]

In order to develop this problem it is necessary to take into account the concepts related to fatigue and compression effort and Goodman equation, i.e, an equation that can be used to quantify the interaction of mean and alternating stresses on the fatigue life of a materia.

With the given data we can proceed to calculate the compression stress:

$\sigma_c = \frac{P}{A}$

$\sigma_c = \frac{160*10^3}{\pi/4*0.05^2}$

$\sigma_c = 81.5MPa$

Through Goodman's equations the combined effort by fatigue and compression is expressed as:

$\frac{\sigma_a}{S_e}+\frac{\sigma_c}{\sigma_u}=\frac{1}{Fs}$

Where,

$\sigma_a=$ Fatigue limit for comined alternating and mean stress

$S_e =$ Fatigue Limit

$\sigma_c=$ Mean stress (due to static load)

$\sigma_u =$ Ultimate tensile stress

$Fs =$ Security Factor

We can replace the values and assume a security factor of 1, then

$\frac{\sigma_a}{320}+\frac{81.5}{400}=\frac{1}{1}$

Re-arrenge for $\sigma_a$

$\sigma_a = 254.8Mpa$

We know that the stress is representing as,

$\sigma_a = \frac{M_c}{I}$

Then,

Where $M_c$ =Max Moment

I= Intertia

The inertia for this object is

$I=\frac{\pi d^4}{64}$

Then replacing and re-arrenge for $M_c$

$M_c = \frac{\sigma_a*\pi*d^3}{32}$

$M_c = \frac{260.9*10^6*\pi*0.05^3}{32}$

$M_c = 3201.7N.m$

Thereforethe moment that can be applied to this shaft so that fatigue does not occur is 3.2kNm

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4 years ago