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A rigid tank contains an ideal gas at 40°C that is being stirred by a paddle wheel. The paddle wheel does 240 kJ of work on the

Sergeu [11.5K]

To solve the problem it is necessary to consider the concepts and formulas related to the change of ideal gas entropy.

By definition the entropy change would be defined as

$\Delta S = C_p ln(\frac{T_2}{T_1})-Rln(\frac{P_2}{P_1})$

Using the Boyle equation we have

$\Delta S = C_p ln(\frac{T_2}{T_1})-Rln(\frac{v_1T_2}{v_2T_1})$

Where,

$C_p$ = Specific heat at constant pressure

$T_1$ = Initial temperature of gas

$T_2$ = Final temprature of gas

R = Universal gas constant

$v_1$ = Initial specific Volume of gas

$v_2$ = Final specific volume of gas

According to the statement, it is an isothermal process and the tank is therefore rigid

$T_1 = T_2, v_2=v_1$

The equation would turn out as

$\Delta S = C_p ln1-ln1$

<em>Therefore the entropy change of the ideal gas is 0</em>

Into the surroundings we have that

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

Where,

Q = Heat Exchange

T = Temperature in the surrounding

Replacing with our values we have that

$\Delta S = \frac{230kJ}{(30+273)K}$

$\Delta S = 0.76 kJ/K$

<em>Therefore the increase of entropy into the surroundings is 0.76kJ/K</em>

8 0

3 years ago

Consider a standard room thermostat. Determine the sensor, transducer, output, and control stages for this measurement system.

Anni [7]

Answer:

Sensor/transducer: bimetallic thermometer

Output: displacement of thermometer tip

Control Tstages: mercury contact switch (open:furnace off; closed:furnace on

Explanation:

for a standard room thermostat : This is the device that sets/determines the temperature of an enclosure.

Sensor/transducer: bimetallic thermometer: Bimetalic thermometer are used for measuring the temperature of the ambient air . bimetallic thermometer actually contains two metals. they undergo linear expansivity as the temperature of the room changes.in other words, they experience contraction and expansion with increase or decrease in temperature.The sensor is basically coupled with a transducer which turns the measured variable(Temperature) into something else, such as a movement on a dial or an electrical signal

Output: displacement of thermometer tip

Controller: mercury contact switch (open:furnace off; closed:furnace on)

once the contact switch is open the furnace can go off. when the contact switch is closed, the furnace will come up.

3 0

3 years ago

What is the differences between stack and queue?

Montano1993 [528]

Answer:

A stack is an ordered list of elements where all insertions and deletions are made at the same end, whereas a queue is exactly the opposite of a stack.

Explanation:

7 0

3 years ago

A hemispherical shell with an external diameter of 500 mm and a thickness of 20 mm is going to be made by casting, located entir

Olenka [21]

Solution :

Given :

External diameter of the hemispherical shell, D = 500 mm

Thickness, t = 20 mm

Internal diameter, d = D - 2t

= 500 - 2(20)

= 460 mm

So, internal radius, r = 230 mm

= 0.23 m

Density of molten metal, ρ = $7.2 \ g/cm^3$

= $7200 \ kg/m^3$

The height of pouring cavity above parting surface is h = 300 mm

= 0.3 m

So, the metallostatic thrust on the upper mold at the end of casting is :

$F=\rho g A h$

Area, A $=2 \pi r^2$

$=2 \pi (0.23)^2$

$=0.3324 \ m^2$

$F=\rho g A h$

$=7200 \times 9.81 \times 0.3324 \times 0.3$

= 7043.42 N

3 0

3 years ago

What is the first test you should do when checking the charging system?

yan [13]

Answer:

Connect the test light in series with the negative post, and start pulling feed wires. The first to check is the heavy charging wire from the alternator. A bad or leaky diode in an alternator is a very common source of overnight battery drain. Connect wires one at a time to see what lead is drawing current.

8 0

2 years ago