HESI A2 Physics Quizlet

Correct Answer: D

Rationale: Step 1: The mechanical power equation is P = E / t, where P is power, E is energy, and t is time. Step 2: Power is the rate at which work is done or energy is transferred. Step 3: The SI unit of power is the watt (W), representing one joule per second. Step 4: Therefore, the correct answer is D: watts. Summary: - A: Ohms is the unit of electrical resistance, not power. - B: Joules is the unit of energy, not power. - C: Volts is the unit of electrical potential difference, not power.

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: To find the object distance, we can use the mirror formula: 1/f = 1/di + 1/do. Given f=2 cm, di=6 cm, we can solve for do. Plugging in the values, we get 1/2 = 1/6 + 1/do. Solving for do, we get do=6 cm. Therefore, the correct answer is B (6 cm). Choice A (3 cm) is incorrect because it does not satisfy the mirror formula equation. Choice C (12 cm) and D (30 cm) are also incorrect as they do not correspond to the calculated object distance of 6 cm.

Correct Answer: D

Rationale: To calculate the repulsive force, use Coulomb's Law: F = k * |q1 * q2| / r^2. Given q1 = 4μC, q2 = 8μC (twice as great), r = 0.5m. Plugging in the values and k = 9 * 10^9 N m^2 / C^2, we get F = 2.5 * 10^−3 N. The correct answer is D. The incorrect choices are A, B, and C because they do not correctly calculate the repulsive force based on the given charges and distances.