HESI Exams Quizlet Physics

Correct Answer: C

Rationale: The correct answer is C because reversible processes can be run in both directions with the same outcome, while irreversible processes cannot. In a reversible process, the system and surroundings can be restored to their original states after the process is reversed, maintaining equilibrium. This is not possible in irreversible processes, where energy dissipation and entropy generation lead to permanent changes. Choices A, B, and D are incorrect because reversible processes can involve heat transfer, do take time, and do not violate the first law of thermodynamics.

Correct Answer: C

Rationale: The correct answer is C: "It operates isothermally at the hot and cold reservoir temperatures." This statement is NOT true about a Carnot cycle. A Carnot cycle consists of four reversible processes: isothermal expansion, adiabatic expansion, isothermal compression, and adiabatic compression. During the isothermal process, the working substance absorbs heat at the hot reservoir temperature and releases heat at the cold reservoir temperature. This process does not occur at the exact temperature of the reservoirs; rather, it occurs at a range of temperatures within each reservoir. As such, the statement that it operates isothermally at the hot and cold reservoir temperatures is incorrect. In summary, the other choices are incorrect because: A is true as efficiency is determined by the reservoir temperatures, B is true as it is a reversible cycle, and D is true as the Carnot cycle is the most efficient heat engine between the same two temperatures.

Correct Answer: C

Rationale: Potential energy increases as particles approach each other because the distance between them decreases, leading to an increase in repulsive forces due to the close proximity of the particles. This causes the potential energy to rise as the particles try to move away from each other to reduce the repulsive forces. Attractive forces do not increase in this scenario, and in fact, they may decrease due to the particles being closer together. Repulsive forces increase as the particles get closer, not decrease. Therefore, the correct answer is C.

Correct Answer: B

Rationale: In an isobaric process (constant pressure), work done is given by W = PΔV. Since the pressure is constant, work done is directly proportional to the volume change. As volume increases, work is done by the system, making it positive. If volume decreases, work is done on the system, making it negative. Choice A is incorrect as work is done even if volume change is zero. Choice C is incorrect as work's sign depends on the direction of volume change. Choice D is incorrect as work done is indeed dependent on pressure and volume change in an isobaric process.

Correct Answer: C

Rationale: The correct answer is C: Gay-Lussac's law. This law states that the pressure of a gas is directly proportional to its temperature when volume is constant. When a car is driven for a long time, the tires heat up due to friction with the road, causing the air inside to heat up as well. According to Gay-Lussac's law, as the temperature increases, the pressure of the gas also increases. Choice A, Boyle's law, states that pressure and volume are inversely proportional at constant temperature. Choice B, Charles' law, states that volume and temperature are directly proportional at constant pressure. Choice D, Dalton's law, is about the total pressure of a gas mixture being the sum of the partial pressures of the individual gases. These laws do not directly explain why the pressure in the tires of a car increases with driving.