EIT Thermodynamics 2

Question 1

A Carnot heat engine operates between a hot reservoir at 800 K and a cold reservoir at 300 K. What is its maximum thermal efficiency?

Accepted Answer

62.5%

Answer

Carnot efficiency = 1 - T_cold/T_hot = 1 - 300/800 = 0.625 = 62.5%.

Question 2

Which thermodynamic process occurs at constant pressure?

Accepted Answer

Isobaric

Answer

An isobaric process occurs at constant pressure, unlike isochoric (constant volume) or isothermal (constant temperature).

Question 3

For an ideal gas undergoing an isentropic (adiabatic reversible) process, which relationship is correct (k = Cp/Cv)?

Accepted Answer

Both B and C

Answer

Both TV^(k-1) = constant and PV^k = constant hold for an isentropic process with an ideal gas.

Question 4

The Clausius inequality states that for any cycle, ∮(δQ/T) is:

Accepted Answer

Equal to zero only for reversible cycles and negative for irreversible cycles

Answer

The Clausius inequality: ∮(δQ/T) ≤ 0, where equality holds for reversible cycles and strict inequality for irreversible cycles.

Question 5

Steam enters a turbine at 3 MPa and 350°C and exits at 100 kPa. Assuming isentropic expansion, which property remains constant through the turbine?

Accepted Answer

Entropy

Answer

An isentropic (reversible adiabatic) process maintains constant entropy.

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