NCERT Solution (Class 11) > Physics Chapter 12 Thermodynamics

NCERT Solution (Class 11) > Physics Chapter 12 Thermodynamics

NCERT Solution Class 11 Physics Chapter 12 Thermodynamics: National Council of Educational Research and Training Class 11 Physics Chapter 12 Solution – Thermodynamics. Free PDF Download facility available at our website.

Board

NCERT
Class

11

Subject

Physics
Chapter

12

Chapter Name

Thermodynamics
Topic

Exercise Solution

Thermodynamics Chapter all Questions and Numericals Solution

 

Chapter 12- Thermodynamics

 

12.3) Explain why

(a) Two bodies at different temperatures T1 and T2 if brought in thermal contact do not necessarily settle to the mean temperature (T1 + T2 )/2.

 (b) The coolant in a chemical or a nuclear plant (i.e., the liquid used to prevent the different parts of a plant from getting too hot) should have high specific heat.

(c) Air pressure in a car tyre increases during driving.

(d) The climate of a harbour town is more temperate than that of a town in a desert at the same latitude.

Answer-

(a) heat transfer always takes place from higher temperature to lower temperature and rate of heat transfer depends upon mass and material of the body .

When two bodies at different temperatures T1 and T2 brought in thermal contact, heat flows from the body at the higher temperature to the body at the lower temperature till equilibrium is achieved . but The equilibrium temperature need not be equal to the mean temperature of the bodies as both bodies may have different mass or material which affects heat transfer rates hence they need not to  attain equilibrium at mean temperature at all time .they can attain the mean temperature only if both bodies have same thermal capacities.

 

(b) Specific heat is defined as amount of heat required to heat the substance by one  gram by one celcius temperature. As coolant is used to take as much heat as possible to avoid heat of other parts of the plant hence it should have high specific heat.

 

(c) Air in tyres has constant volume. During driving  the air temperature inside the tyre increases. According to Charles’ law, at constant volume, temperature is directly proportional to pressure. Hence, if the temperature inside a tyre increases, then the air pressure will also increase.

 

 (d) The relative humidity in a harbour town is more than it is in a desert town. Hence the climate of a harbour town is more temperate than that of a town in a desert at the same latitude.

 

12.4)

 

12.5)

 

In case you are missed :- Previous Chapter Solution

 

12.6) Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains a gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stopcock is suddenly opened. Answer the following :

 (a) What is the final pressure of the gas in A and B ?

 (b) What is the change in internal energy of the gas ?

 (c) What is the change in the temperature of the gas ?

(d) Do the intermediate states of the system (before settling to the final equilibrium state) lie on its P-V-T surface ?

Answer-

(a) when the stopcock between cylinders A and B is opened. The volume available to the gas is doubled. Since volume is inversely proportional to pressure, the pressure will become half of the original value. At standard temperature is 1 atm. Hence new pressure will be 0.5 atm.

 

(b) in this case net work done is zero hence no change in internal energy of system.

 

(c) Since no work is done by the gas during the expansion of the gas, the temperature of the gas will not change at all.

 

(d) Given expansion is  free expansion free expansion is rapid process which does not obey gas equation. The intermediate states do not satisfy the gas equation and since they are in non states, they do not lie on the P-V-T surface of the system.

 

12.7)

 

12.8)

 

12.10)

In case you are missed :- Next Chapter Solution

Updated: April 17, 2023 — 11:44 am

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