Laws of Thermodynamics

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Q1. What is the relationship between temperature and kinetic energy in gases?

Solution:

The average kinetic energy of gas molecules is directly proportional to the temperature of the gas.

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Q2. What does the second law of thermodynamics state about entropy?

Solution:

The second law of thermodynamics states that the entropy of an isolated system always increases over time.

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Q3. In a heat engine, what is the work done equal to?

Solution:

The work done by a heat engine is equal to the heat input minus the heat output.

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Q4. If the entropy of a system increases, what can be inferred about the system?

Solution:

An increase in entropy indicates that the system is becoming more disordered.

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Q5. According to the third law of thermodynamics, what happens as the temperature approaches absolute zero?

Solution:

The third law states that as the temperature approaches absolute zero, the entropy of a perfect crystal approaches zero.

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Q6. What is the work done by a gas that expands isothermally from volume V1 to V2 at temperature T?

Solution:

For isothermal expansion, the work done is given by W = nRT ln(V2/V1).

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Q7. In a heat engine, if the input heat is 800 J and the output work is 300 J, what is the efficiency?

Solution:

Efficiency = Work output / Heat input = 300 J / 800 J = 0.375 or 37.5%.

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Q8. What is the relationship between heat transfer and temperature difference in a conductor?

Solution:

Heat transfer through conduction is directly proportional to the temperature difference between the ends of the conductor.

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Q9. In an isothermal process, what remains constant?

Solution:

In an isothermal process, the temperature of the system remains constant.

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Q10. Which of the following is a consequence of the third law of thermodynamics?

Solution:

The third law of thermodynamics implies that absolute zero cannot be reached, as the entropy of a perfect crystal approaches zero.