Nursing Elites

1. What is the main difference between a reversible and irreversible process in thermodynamics?

• A. Reversible processes involve heat transfer, while irreversible processes do not.
• B. Reversible processes occur instantaneously, while irreversible processes take time.
• C. Reversible processes can be run in both directions with the same outcome, while irreversible processes cannot.
• D. Reversible processes violate the first law of thermodynamics.

Correct answer: C

Rationale: A reversible process is an idealized process that can be reversed without leaving any change in either the system or the surroundings. In contrast, irreversible processes cannot be reversed and often involve entropy production or dissipation. Choice A is incorrect because both reversible and irreversible processes can involve heat transfer. Choice B is incorrect as the speed of a process does not determine its reversibility. Choice D is incorrect because reversible processes do not violate the first law of thermodynamics; they comply with it by maintaining a balance between energy inputs and outputs. Therefore, the correct answer is C, as it accurately captures the main difference between reversible and irreversible processes in thermodynamics.

2. When two identical charged spheres, both positively charged, are brought close together, the electrostatic force between them will be:

• A. Slightly attractive
• B. Zero
• C. Strongly attractive
• D. Strongly repulsive

Correct answer: D

Rationale: When two positively charged spheres are brought close together, they will experience a repulsive force due to their like charges. The electrostatic force causes the spheres to repel each other, making the correct answer D: Strongly repulsive. The force is not dependent on the material of the spheres, and the force is definitely not zero, as like charges repel. Choice A is incorrect as like charges do not attract each other. Choice C is incorrect as like charges repel, not attract.

3. What is the kinetic energy of a 500-kg wagon moving at 10 m/s?

• A. 50 J
• B. 250 J
• C. 2.5 × 10^4 J
• D. 5.0 × 10^5 J

Correct answer: C

Rationale: The formula for calculating kinetic energy is KE = 0.5 × mass × velocity². Given the mass of the wagon is 500 kg and the velocity is 10 m/s, we can substitute these values into the formula: KE = 0.5 × 500 kg × (10 m/s)² = 0.5 × 500 kg × 100 m²/s² = 25,000 J or 2.5 × 10⁴ J. Therefore, the kinetic energy of the 500-kg wagon moving at 10 m/s is 2.5 × 10⁴ J. Choice A (50 J) is incorrect because it is too low; Choice B (250 J) is incorrect as it does not match the correct calculation; Choice D (5.0 × 10^5 J) is incorrect as it is too high. The correct answer is C (2.5 × 10^4 J).

4. The Prandtl number (Pr) is a dimensionless property relating:

• A. Viscosity and thermal diffusivity
• B. Density and pressure
• C. Surface tension and pressure
• D. Reynolds number and flow regime

Correct answer: A

Rationale: The Prandtl number (Pr) is a dimensionless number used to characterize fluid flow. It is the ratio of momentum diffusivity to thermal diffusivity. In simpler terms, it relates the ability of a fluid to conduct heat to its ability to conduct momentum. Therefore, the correct relationship is between viscosity and thermal diffusivity, making choice A the correct answer. Choices B, C, and D are incorrect because they do not represent the properties that the Prandtl number relates.

5. The triple point of a substance is the specific temperature and pressure at which all three phases (solid, liquid, and gas) can coexist in thermodynamic equilibrium. Which of the following statements about the triple point is true?

• A. It can vary depending on the container size.
• B. It is a unique point for each pure substance.
• C. The pressure at the triple point can be zero for some substances.
• D. The temperature at the triple point can be above the boiling point of the liquid phase.

Correct answer: B

Rationale: The triple point is a unique temperature and pressure where all three phases (solid, liquid, and gas) of a pure substance can coexist in equilibrium. It is a constant for each substance and independent of container size. Choice A is incorrect because the triple point is a fixed point regardless of the container size. Choice C is incorrect as the pressure at the triple point is specific for each substance and will not be zero unless the substance has unique properties. Choice D is incorrect since the temperature at the triple point is precisely defined and cannot be above the boiling point of the liquid phase.

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