Thermodynamics Questions

• Gas law check (Gay-Lussac/Amontons law): judge the statement Statement: “For a perfect gas at constant volume, p/T = constant.” Choose whether the statement is correct or incorrect.
• Irreversibility versus heat loss: judge the statement Statement: “There is a loss of heat in an irreversible process.” Choose whether the statement is correct or incorrect.
• Fuel sources: decide correctness of the statement Statement: “All the commercial liquid fuels are derived from natural petroleum (crude oil).” Choose whether the statement is correct or incorrect (as per conventional thermal-engineering classification).
• Diesel versus Otto cycle: effect of cut-off ratio on efficiency Fill the blank: “When the cut-off ratio is _____, the efficiency of the Diesel cycle approaches the Otto cycle efficiency.” Choose the correct value.
• Simple Brayton (gas turbine) cycle: typical performance How are the thermal efficiency and the work ratio of a simple (un-regenerated, un-intercooled, un-reheated) gas turbine cycle generally characterized? Choose the best description.
• Open systems and mass transfer: name the process type Definition prompt: “Processes occurring in an open system that permit transfer of mass to and from the system are known as …” Choose the correct term.
• Ratio of specific heats γ = cp/cv: decide its magnitude For a gas, compare the ratio of specific heats γ = c_p/c_v with unity. Choose the correct relation.
• Universal gas constant vs. specific gas constant: verify the relationship Statement: The universal gas constant of a gas equals the product of the gas’s molecular mass and its (specific) gas constant per unit mass. Choose whether the statement is correct or not.
• Isothermal process law: identify the governing gas law For an isothermal (constant-temperature) process of an ideal gas, select the correct law that applies. Choose the correct option.
• Thermal efficiency comparison: Stirling cycle versus Carnot cycle State how the efficiency of the (reversible, regenerator-based) Stirling cycle compares with a Carnot cycle operating between the same temperature limits. Choose the correct relationship.
• Second law of thermodynamics – Kelvin–Planck statement Which of the following correctly expresses the Kelvin–Planck statement of the second law of thermodynamics for heat engines operating in a cycle?
• Thermodynamic diagrams – area under the T–s curve On a temperature–entropy (T–s) diagram, the area under the process curve between two entropy states represents which thermodynamic quantity for that process?
• Perfect gas relationships – Boyle’s law identification For a perfect gas, which relation expresses Boyle’s law when absolute temperature T is held constant (isothermal process)?
• Gay–Lussac (pressure) law – proportionality at constant volume According to the pressure law, the absolute pressure of a fixed mass of a perfect gas varies __________ with its absolute temperature when the volume is held constant.
• Air-Standard Diesel Cycle – Parameters Governing Thermal Efficiency In the ideal (air-standard) Diesel cycle, the thermal efficiency primarily depends on the compression ratio as well as the cut-off ratio (for a given specific heat ratio of the working gas).
• First Law for a Closed Gas System (General Gas Energy Equation) Between states 1 and 2, the heat supplied equals the change in internal energy plus the work done: Q1–2 = dU + W1–2 (with consistent heat units).
• Air-Standard Dual (Mixed) Combustion Cycle – Process Count Check The ideal dual combustion cycle comprises two isentropic processes, two constant-volume processes (heat addition and heat rejection), and one constant-pressure process (part of the heat addition).
• Thermal Equilibrium Transitivity – Name of the Law If two bodies are each in thermal equilibrium with a third body, then they are in thermal equilibrium with each other. This fundamental statement is known as the Zeroth law of thermodynamics.
• Kelvin–Planck Statement – What It Addresses Kelvin–Planck's statement of the second law deals with the impossibility of complete conversion of heat into work in a cyclic engine (limits on conversion of heat to work).
• Definition – Expansion Ratio in a Thermodynamic Process If v1 is the volume at the beginning of expansion and v2 is the volume at the end of expansion, then the expansion ratio r is defined as r = v2 / v1.