In a temperature range near some absolute temperature T, the tension force F of a stretched plastic rod is related its length l by the expression

F = aT 2(L-Lo) where a and Lo are positive constants, Lo being the unstretched length of the rod. When L Lo, the heat capacity to its length L by the expression CL of the rod (measured at constant length) is given by the relation CL bT, where b is a constant. A. Write down the fundamental thermodynamic relation for this system, expressing dS in terms of dL and dE. B. The entropy S(T,L) of the rod is a function of T and L. Compute c. Knowing S(To, Lo), find S(T, L) at any other temperature T and length L. (It is most convenient to calculate first the change of entropy with temperature at the length Lo where the heat capacity is known. ) d. If you start at T-T, and L = Li and stretch the thermally insulated rod quasi-statically until it attains the length L, what is the final temperature Ty? e. Calculate the heat capacity CL(L, T) of the rod when its length is L instead of Lo f. Calculate S(T,L) by writing S(T, L)-S(TyLo) = [S(T, L)-S(Tp, L)] + [S(Tp, L)-S(TO, Lo)] and using the result of part (e) to compute the first term in square brackets. Show that the final answer agrees with the one found in part (c)

Answers

Answer 1

a) The fundamental thermodynamic relation for this system is given by dS = (1/T)dE + (F/T)dL, where S is the entropy, E is the internal energy, T is the temperature, F is the tension force, and L is the length of the rod.

b) To compute the entropy S(T, L), we need to integrate dS. Since the heat capacity CL is given by CL = bT, we have dE = CL(T,L)dT. Substituting this in the fundamental relation, we get dS = (b/T)L(T,L)dT + (aT/T)L(T,L)dL. Integrating both sides gives S(T, L) = S(To, Lo) + bL[ln(T/To)] + a/2L[ln(L/Lo)].

c) To find S(T, L), we first find the change in entropy with temperature at the length Lo where the heat capacity is known: dS = (b/T)Lo dT. Integrating this expression from To to T gives S(T,Lo) - S(To,Lo) = bLo[ln(T/To)], which we can use to find S(T,L) using the expression in part (b).

d) Since the rod is thermally insulated, we have dE = 0, so the fundamental relation reduces to dS = (F/T)dL. Integrating this expression from Li to L gives S(Ty, L) - S(T-T, Li) = [tex][a/2(Ty^2 - (T-T)^2)[/tex]- F(Li-L)]/T, where Ty is the final temperature.

e) The heat capacity CL(L, T) is given by CL = bT, where b is a constant.

f) Using the result from part (e), we have CL(T, L) = [tex]CL(Ty, Lo)(Lo/L)^2[/tex]. Substituting this expression in the equation in part (b) gives S(T, L) - S(Ty, Lo) = bLo[ln(T/To) - 2ln(L/Lo)] + a/2[ln(L/Lo)]. Using the result from part (c) to simplify the first term, we get S(T, L) - S(Ty, Lo) = bL[ln(T/Ty)] + a/2[ln(L/Lo)], which agrees with the result in part (b).

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Related Questions

g what is the angular velocity (in rad/s) of a 62.0 cm diameter tire on an automobile traveling at 93.5 km/h? (enter the magnitude.)

Answers

The angular velocity of the tire is 84.02 rad/s

To find the angular velocity of the tire, we need to convert the linear velocity of the automobile into angular velocity of the tire using the formula:v = ωrwhere v is the linear velocity, ω is the angular velocity, and r is the radius of the tire.First, we need to convert the speed of the car from km/h to m/s:93.5 km/h = 26.0 m/sThe radius of the tire is half the diameter:r = 0.5(62.0 cm) = 0.31 mSubstituting these values into the formula, we get:26.0 m/s = ω(0.31 m)Solving for ω, we get:ω = 84.02 rad/sTherefore, the angular velocity of the tire is 84.02 rad/s.In physics, the rotational velocity or angular velocity ( or ), also known as the angular frequency vector, is a pseudovector representation of how quickly an object spins or revolves in relation to a point or axis.

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in the following equation, a is acceleration, m is mass, v is velocity, r is radius, t is time, is an angle, and c is a constant. a=c mv2sin0/rtif this equation is valid, which of the following could be the units of c?a.s/kgb.m/s2c.m2/sd.kg/me.kg m/s2

Answers

The units of c are: [c] = m²/s³. The answer is b.

The given equation is a = cmv²sinθ/rt, where a is acceleration, m is mass, v is velocity, r is radius, t is time, θ is an angle, and c is a constant.

To determine the units of c, we can analyze the units of each term in the equation and then determine the units of c such that the units of the equation are consistent.

Units of each term in the equation are:

a: m/s²

m: kg

v: m/s

r: m

t: s

sinθ: dimensionless

Substituting these units in the given equation, we get:

[m/s²] = [c] x [kg] x [m/s]² x [dimensionless] / [m] x [s]

Simplifying the above equation, we get:

[c] = [m/s²] x [m] x [s] / [kg] x [m/s]² x [dimensionless]

Therefore, the units of c are:

[c] = m²/s³

Hence, option (b) m²/s³ could be the units of c.

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a potential difference of 0.020 v is developed across the 10-cm -long wire of (figure 1) as it moves through a magnetic field perpendicular to the plane of the figure. figure1 of 1 a horizontal 10 centimeter long wire segment has positive charges on the left end and negative charges on the right end. the segment moves vertically upward with a velocity of 5.0 meters per second. part a what is the strength of the magnetic field?

Answers

If the segment moves vertically upward with a velocity of 5.0 meters per second, the strength of the magnetic field is 0.040 T.

To solve for the strength of the magnetic field, we need to use the equation:

EMF = B*L*V

where EMF is the potential difference developed across the wire, B is the strength of the magnetic field, L is the length of the wire, and V is the velocity of the wire.

Substituting the given values, we get:

0.020 V = B*(10 cm)*(5.0 m/s)

First, we need to convert the length of the wire from centimeters to meters:

L = 10 cm = 0.1 m

Substituting this value, we get:

0.020 V = B*(0.1 m)*(5.0 m/s)

Simplifying, we get:

B = 0.020 V / (0.1 m * 5.0 m/s)

B = 0.040 T

Therefore, the strength of the magnetic field is 0.040 T.

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what do you do for labored, contstriction, or lack of tidal volume

Answers

If someone is experiencing labored breathing, constriction, or a lack of tidal volume, it could indicate an underlying medical issue that needs to be addressed by a healthcare professional. In the meantime, some strategies that may help include relaxation techniques such as deep breathing exercises, and using an inhaler or nebulizer if prescribed.

Ensuring proper posture to facilitate breathing, and avoiding triggers such as smoke or allergens. It is important to seek medical attention if these symptoms persist or worsen.

Thus, If you are experiencing labored breathing, constriction in the airways, or a lack of tidal volume, you should take the following steps:-

1. Stay calm: Try to remain calm and composed, as anxiety can exacerbate your symptoms.

2. Assess your environment: Ensure that you are in a well-ventilated area free from allergens, pollutants, or irritants that could be contributing to your symptoms.

3. Practice deep breathing: Focus on slow, deep breaths. Inhale through your nose and exhale through your mouth to help regulate your breathing and increase tidal volume.

4. Sit or stand upright: Maintaining an upright posture can help to alleviate constriction and improve airflow.

5. Seek medical attention: If your symptoms persist or worsen, consult a healthcare professional for further evaluation and treatment. They may recommend medications or therapies to alleviate constriction and improve tidal volume.

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An object is placed in front of a concave mirror, between the center of
curvature of the mirror and its focal point, as shown in the diagram below.
Three light rays are traced, along with their corresponding reflected rays.
Which statement below best describes the image formed?

Answers

The image formed by the concave mirror is enlarged or magnified.

optionC.

What type of image is formed?

When an object is placed in front of a concave mirror, between the center of curvature of the mirror and its focal point, the image formed by the concave mirror has the following characteristics;

the image formed is beyond the center of curvature. the image formed is realthe image formed is invertedthe image formed is magnified

So based on the given options, we can that the option that falls in the characteristics given above is "the image is enlarged or magnified.

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