Thermodynamics Help: Ideal Gas Temperature Rise Comparison

In summary, the rise in temperature of the gas in cylinder B is 70K, which is the correct answer. This is because all the heat supplied is used to raise the internal energy of the gas in cylinder B, while some of the heat is used to do work against the piston in cylinder A. The ratio of the change in temperature of B to that of A is Cp/Cv = 5/3, which results in a temperature change of 70K for cylinder B.
  • #1
zorro
1,384
0

Homework Statement



Two cylinders A and B fitted with pistons contain equal number of moles of an ideal monoatomic gas at 400K. The piston of A is free to move while that of B is held fixed. Same amount of heat energy is given to the gas in each cylinder. If the rise in temperature of the gas in A is 42K, the rise in temperature of the gas in B is

a)21K
b)35K
c)42K
d)70K

The Attempt at a Solution



Going by the options, the answer should be d) because the entire heat supplied is used to raise the internal energy of the gas in container B where as some part of it is used to do work against the piston in container A (work on expansion). But this is incorrect.
 
Physics news on Phys.org
  • #2


Abdul Quadeer said:

Homework Statement



Two cylinders A and B fitted with pistons contain equal number of moles of an ideal monoatomic gas at 400K. The piston of A is free to move while that of B is held fixed. Same amount of heat energy is given to the gas in each cylinder. If the rise in temperature of the gas in A is 42K, the rise in temperature of the gas in B is

a)21K
b)35K
c)42K
d)70K

The Attempt at a Solution



Going by the options, the answer should be d) because the entire heat supplied is used to raise the internal energy of the gas in container B where as some part of it is used to do work against the piston in container A (work on expansion). But this is incorrect.
d) is the correct answer. The ratio of the temperature of B to that of A is Cp/Cv = 5/3. 5x42/3 = 70

AM
 
  • #3


Thanks!
 
  • #4


Andrew Mason said:
d) is the correct answer. The ratio of the temperature of B to that of A is Cp/Cv = 5/3. 5x42/3 = 70
I meant to say of course that the ratio of the "change in" temperature of B to that of A is Cp/Cv.

AM
 
  • #5


I would like to point out that the rise in temperature of the gas in B is actually 42K, the same as in A. This is because in an ideal gas, the internal energy only depends on the temperature, not on the volume or pressure. Therefore, even though the piston in B is held fixed and no work is done, the heat energy supplied will still result in an increase in temperature of the gas in B. This is known as the first law of thermodynamics, which states that the change in internal energy of a system is equal to the heat added to the system minus the work done by the system. In this case, the work done by the gas in A is equal to the heat added, resulting in a rise in temperature of 42K, and the same applies to B. Therefore, the answer is c) 42K.
 

What is thermodynamics?

Thermodynamics is the study of energy and its transformations, including heat and work, in physical systems.

What are the laws of thermodynamics?

The laws of thermodynamics are fundamental principles that govern the behavior of energy in physical systems. They include the laws of conservation of energy, entropy, and energy transfer.

What are some real-world applications of thermodynamics?

Thermodynamics has many practical applications, such as designing more efficient engines and refrigeration systems, studying the behavior of materials at high temperatures, and understanding the processes involved in chemical reactions.

How can I calculate the efficiency of a thermodynamic system?

The efficiency of a thermodynamic system can be calculated by dividing the work output by the heat input. This is known as the Carnot efficiency and is a theoretical maximum for any system operating between two temperatures.

What is the difference between heat and temperature in thermodynamics?

Heat is a form of energy that is transferred from one object to another due to a temperature difference. Temperature, on the other hand, is a measure of the average kinetic energy of the particles in a system. In thermodynamics, heat is a form of energy while temperature is a measure of the intensity of heat.

Similar threads

  • Introductory Physics Homework Help
Replies
33
Views
1K
  • Introductory Physics Homework Help
Replies
8
Views
663
  • Introductory Physics Homework Help
Replies
1
Views
440
  • Introductory Physics Homework Help
Replies
2
Views
461
  • Introductory Physics Homework Help
Replies
8
Views
1K
  • Introductory Physics Homework Help
Replies
8
Views
870
  • Introductory Physics Homework Help
Replies
1
Views
841
  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
10
Views
712
  • Introductory Physics Homework Help
Replies
16
Views
1K
Back
Top