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[QUE/TH-06009] TH-PROBLEM

Node id: 5204page

In the compression stroke of a Diesel engine, air is
compressed from atmospheric pressure and room temperature to about
${1\over 15}$ of its original volume. Find the final temperature,
assuming a reversible adiabatic compression.

AK-47's picture 22-01-20 10:01:18 n

[QUE/TH-02012] TH-PROBLEM

Node id: 5203page

In the Fig.-2, let $P_2=10\times10^5$Nm$^{-2}$, $P_1=4\times10^5$Nm$^{-2}$, $v_1=2.5$m$^3$kilomole$^{-1}$. Find

  1. the temperature $T$,
  2. the specific volume $v_2$,
  3. the temperature at points $b$ and $d$,
  4. the actual volume $V$ at point $a$ if the system consists of 4 kilomoles of hydrogen,
  5. the mass of hydrogen.
AK-47's picture 22-01-20 09:01:47 n

[QUE/TH-02011] TH-PROBLEM

Node id: 5202page

Fig.-2 shows five processes, $a-b,~b-c,~c-d,~d-a,~a-c$,
plotted in the $P-v$ plane for an ideal gas in a closed system. Show
the same processes (a) in the $P-T$ plane. (b) in the $T-v$

AK-47's picture 22-01-20 09:01:44 n

[QUE/TH-02010] TH-PROBLEM

Node id: 5201page

The $U$-tube in Fig.-1 below, of uniform cross section 1 cm$^2$, contains mercury to the depth shown. The barometric pressure is 750 Torr. The left side of the tube is now closed at the top, and the right side in connected to a good vacuum pump. Assuming that the temperature remains constant answer the following questions.

  1. How far does the mercury level fall in the left side?
  2. What is final pressure of the trapped air? 
AK-47's picture 22-01-20 09:01:18 n

[QUE/TH-02009] TH-PROBLEM

Node id: 5200page

The table below lists corresponding values of the pressure and specific volumes of steam at three temperatures of 700$^\circ$F, 1150$^\circ$F and 1600$^\circ$F. Without converting the MKS units, compute the ratio $Pv/T$ at each temperature and pressure; and for each temperature plot theses ratios as a function of pressure. Estimate the extrapolated value of $Pv/T$ as $P$ approaches zero, and find the value of $R$ in $J$ kilomoles $K^{-1}$.

{$P$} {$t=700^\circ$F} {$t=1150^\circ$F} {$t=1600^\circ$F}
\{$lb~in^{-2}$} {$v~ft^3~lb^{-1}$} {$v~ft^3~lb^{-1}$} {$v~ft^3~lb^{-1}$}
500 1.3040 1.888 2.442
1000 0.6080 0.918 1.215
2000 0.2490 0.449 0.601
3000 0.0984 0.289 0.397
4000 0.0287 0.209 0.294
5000 0.0267 0.161 0.233
  371.1$^\circ$C 621.1$^\circ$C 871.1$^\circ$C
 

 

 

AK-47's picture 22-01-20 09:01:29 n

[QUE/TH-02008] TH-PROBLEM

Node id: 5199page

An approximate equation of state of a real gas at moderate
pressures, devised to take into account of the finite size of the
molecules, is $P(v-b)=R\theta$, where $R$ and $b$ are constants.
Show that

\begin{equation*}
\beta = {1/\theta\over 1+bP/(R\theta)}~~,~~~~\chi =
{1/P\over1+bP/(R\theta)}
\end{equation*}

AK-47's picture 22-01-16 17:01:49 n

[QUE/TH-02007] TH-PROBLEM

Node id: 5198page

The fundamental frequency of vibration of a wire of length
$L$, mass $m$, and tension $\mathcal{J}$ is given by
$$
f_1={1\over2L} \sqrt{{\mathcal{J}L\over m}}
$$
With what frequency of vibration with the wire of Prob. [2] vibrate
at 20$^\circ$C; $8^\circ$C? (The density of wire is $9.0\times10^3$
kg/m$^3$)

AK-47's picture 22-01-16 17:01:47 n

[QUE/TH-02006] TH-PROBLEM

Node id: 5197page

A metal wire of cross-sectional area 0.0085 cm$^2$ under a
tension of 20 N and a temperature of 20$^\circ$C is stretched
between two rigid supports 1.2 m apart. If the temperature is
reduced to 8$^\circ$C, what is the final tension? (Assume that
$\alpha$ and $Y$ remain constant at the values
$1.5\times10^{-5}$K$^{-1}$ and $2.0\times10^9$ N/m$^2$ respectively)

AK-47's picture 22-01-16 17:01:07 n

[QUE/TH-02005] TH-PROBLEM

Node id: 5196page

A wire undergoes an infinitesimal change from an initial
equilibrium state to a final equilibrium state, show that the
change of tension is equal to
$$
d\mathcal{J} = -\alpha A Y d\theta + {AY\over L} ~dL
$$

AK-47's picture 22-01-16 17:01:39 n

[QUE/TH-02004] TH-PROBLEM

Node id: 5195page

A metal, whose volume expansivity is 5.0$\times10^{-5}$ K$^{-1}$ and isothermal compressibility is $1.2\times10^{-11}$Pa$^{-1}$, is at a pressure of $1\times10^5$ Pa and a temperature of 20$^\circ$C. A thick surrounding cover of invar, of negligible compressibility and expansivity, fit is very snugly.

  • [(a)] What will be the final pressure if the temperature is raised to 32$^\circ$C?
  • [(b)] If the cover can with stand a maximum pressure of $1.2\times10^8$Pa, what is the highest temperature two which the system may be raised?

 

AK-47's picture 22-01-16 17:01:17 n

[QUE/TH-02003] TH-PROBLEM

Node id: 5194page

An approximate equation of state of a real gas at moderate pressures is given by $$ P_v = R\theta\left(1+{B\over v}\right) $$ where $R$ is a constant and $B$ is a function of $\theta$ only.  Show that

  • [(a)] $\beta=\dfrac{1}{\theta}\left(v+B+\theta~\dfrac{dB}{d\theta}\right)\biggl/(v+2B)$
  • [(b)] $\kappa = \dfrac{1} {P} ~\dfrac{1}{(1+BR\theta/Pv^2)}$ \hfill{[7]}
AK-47's picture 22-01-16 17:01:02 n

[QUE/TH-02002] TH-PROBLEM

Node id: 5193page

For a gas satisfying van de Waals equation
$$
\left(P+{a\over v^2}\right) (v-b) = R\theta
$$
show that the critical temperature $\theta_c$, critical pressure
$P_c$, and the critical volume are given by

$\theta_c =
{8a\over27Rb}~,~~P_c={a\over27b^2}~,~~v_c=3b\,.\,.$

 

AK-47's picture 22-01-16 17:01:29 n

[QUE/EM-05001] EM-PROBLEM

Node id: 5192page

Determine the polarizability of  to charges that are bound together by a harmonic potential with force constant \(k\).

kapoor's picture 22-01-16 13:01:42 n

[QUE/EM-04013] EM-PROBLEM

Node id: 2390page

A sphere of radius \(R_1\) has charge uniformly distributed throughout its volume except for a smaller charge-free spherical volume of radius \(R_2 < R_1\) located entirely within the big sphere. Show that the electric field at all points inside the small sphere is a constant.

Zangwill

kapoor's picture 22-01-16 07:01:25 n

[QUE/EM-04012] EM-PROBLEM

Node id: 2384page

 A spherical shell is cut into two hemispheres which are glued  with an insulated boundary. The potentials of the hemispheres  is kept at constant values \( V_0\)  for \(0\lt \theta\lt \pi/2\) and at \(-V_0\) for \(\pi/2 \lt \theta \lt \pi\).  Use Green function in spherical coordinates to find the potential at an arbitrary point.

 

RamMohan

kapoor's picture 22-01-16 07:01:01 n

[QUE/EM-04005] EM-PROBLEM

Node id: 2379page

A conducting spherical shell of radius \(a\) is placed in a uniform field \(vec{E}\). Show that the force tending to separate two halves of the sphere across a diametrical plane perpendicular to \(\vec{E}\) is given by \[ F = \frac{9}{4}\pi \epsilon_0a^2 E^2.\]

Panofsky and Philips

kapoor's picture 22-01-16 06:01:40 n

[QUE/EM-10005] --- EM-PROBLEM

Node id: 3015page

An inductor, made up of a very long air-core solenoid of length $\ell$, radius $r$ and  $n$  turns  per  unit  length, carries a current $I$.  For  $\frac{dI}{dt}>0$,  verify  that \begin{equation}  \frac{dU_B}{dt} = -\iint_S \vec{S}.\overrightarrow{dA}, \end{equation}  where the surface $S$ in the surface integral in the right hand side is the surface that encloses the solenoid and \(U_B\) is the energy density associated with the magentic field.

Analysis

You need to understand the following. Read the given question several times and answer the following questions. After making sure that you have correct answers and that you understand them as well, try to solve the problem.

  1. What is Poynting theorem?
  2. What does $\vec{S}$ in \EqRef{EQ02} stand for?
  3. What is the expression of the Poynting vector?
  4. What physical quantities do the symbols $U_B$ and $\vec{S}$, in \EqRef{EQ02}, represent?
  5. Is it correct that the expressions for the quantities $\vec{S}$ and $U_B$ involve $\vec{E}$ and $\vec{B}$? If not, what is the correct expression?
  6. What field(s) does the solenoid produce? Magnetic field $\vec{B}$? Electric field $\vec{E}$? Both of these? None of these? Do you know the expressions?
  7. Compute the magnetic field produced by the solenoid. Write zero as your answer if it does not produce it.
  8. Repeat the above question for the electric field.
  9. Find $\vec{S}$ in terms of current $I$ and compute the surface integral $\iint_S \vec{S}.\overrightarrow{dA}$. Find $\vec{S}$ on the sutface of the solenoid.
  10. What will be the volume integral of $U_B$?
kapoor's picture 22-01-15 22:01:40 n

[QUE/TH-01006] TH-PROBLEM

Node id: 5191page

In the table below, a number in the top row represents the
pressure of a gas in the bulb of a constant volume gas thermometer
when the bulb is immersed in the triplet cell. The bottom row
represents the corresponding readings of the pressure when the bulb
is surrounded by a material at constant unknown temperature.
Calculate the ideal gas temperature of this material (use five
significant figures) {Zemansky}

 $P_{TP}$,~ mm Hg 1000.00 750.00 500.00 250.00
 $P_{TP}$, mm Hg 1535.30 1151.60 767.82 383.95
 

 Is it necessary to convert the

pressures from mm Hg to Pascal?

AK-47's picture 22-01-14 14:01:00 n

[QUE/TH-01005] TH-PROBLEM

Node id: 5190page

A new scale is to defined in terms of ideal gas scale of
temperature. Let the difference of ice points and the steam points
be fixed at $t_s-t_i=180$ deg. If
$\displaystyle{\lim_{P_{TP}\to0}\left({P_s\over P_i}\right)}$ is
given to be 1.3661 as the best experimental value, find $t_s$ and
$t_i$ on the new scale.

AK-47's picture 22-01-14 14:01:30 n

[QUE/TH-13005] TH-PROBLEM

Node id: 5188page

A box of volume $2V$ is divided into equal halves by a thin partition. The left side contains perfect gas at pressure $p_L$ and the right side is vacuum. A small hole of area $A$ is punched in the partition at time $t\,=\,0$. What is the pressure in the left had side $p_L(t)$ after a time t ?. Assume the temperature to be constant on both the sides as $T$. Assume Maxwell- Boltzmann statistics.

AK-47's picture 22-01-14 13:01:08 n

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