HESI A2 Physics Quizlet

Correct Answer: A

Rationale: The correct answer is A because a refrigerator operates on a Carnot cycle, which involves removing heat from a cold reservoir at a lower temperature. This aligns with the basic principle of how refrigerators work, by transferring heat from inside the refrigerator to the outside environment. Choice B is incorrect because refrigerators do not create cold; they simply transfer heat. Choice C is incorrect because refrigerators actually decrease the total entropy in the system by cooling the inside of the refrigerator. Choice D is incorrect as refrigerators do not operate isothermally at both the hot and cold reservoirs; there is a temperature difference between the two reservoirs to allow for heat transfer.

Correct Answer: B

Rationale: The Reynolds number (Re) is used to characterize the flow regime of a fluid, determining if it is laminar or turbulent. It is calculated as the ratio of inertial forces to viscous forces. For low Re, flow is laminar, while for high Re, flow is turbulent. Surface tension (C) and buoyancy force (D) do not directly relate to Re. Fluid density (A) affects the Reynolds number indirectly through viscosity.

Correct Answer: B

Rationale: The correct answer is B: Ketchup. Ketchup is a common example of a shear-thinning fluid because its viscosity decreases under shear stress. When force is applied to ketchup, its resistance decreases, making it easier to flow. This behavior is characteristic of shear-thinning fluids, where viscosity decreases with increasing shear rate. Water (Choice A) is a Newtonian fluid with constant viscosity, while Air (Choice C) and Alcohol (Choice D) do not exhibit shear-thinning behavior. Therefore, B is the correct choice.

Correct Answer: C

Rationale: Step-by-step rationale for why choice C is correct: 1. The first law of thermodynamics is based on the principle of energy conservation. 2. Choice C accurately reflects this principle by stating that energy cannot be created or destroyed, only transferred or transformed. 3. This is in line with the law of conservation of energy, which is a fundamental concept in physics. 4. Choices A, B, and D are incorrect because they do not accurately represent the first law of thermodynamics. 5. Choice A violates the principle of conservation of energy, choice B refers to the second law of thermodynamics, and choice D is not directly related to the first law.

Correct Answer: D

Rationale: To calculate power, we use the formula P = W / t, where P is power, W is work done, and t is time taken. The correct formula is D: P = F / t. Power is the rate at which work is done, so it is the work done per unit time. Therefore, the correct formula depicts power as the force applied divided by the time taken to do the work. Incorrect choices: A: P = W / F - This formula is incorrect because power is not work divided by force. B: P = d / t - This formula is incorrect because power is not distance divided by time. C: P = W x t - This formula is incorrect because power is not work multiplied by time. In summary, choice D is correct because power is defined as work done per unit time, which is represented by force divided by time.