HESI A2 Physics

Correct Answer: A

Rationale: The correct answer is A because laminar flow is characterized by smooth, parallel layers of fluid particles moving in a uniform manner without mixing. This flow pattern occurs at low Reynolds numbers, where viscous forces dominate over inertial forces. Option B is incorrect as it describes turbulent flow, which is characterized by erratic and chaotic motion. Option C is incorrect because high viscosity would lead to more laminar flow, not hinder it. Option D is incorrect as incompressibility is a property of fluids and does not specifically characterize laminar flow.

Correct Answer: B

Rationale: The correct answer is B: Conduction. When the hot cup of coffee is placed on a cold table, heat transfer primarily occurs through conduction. This is because heat is transferred from the hot coffee to the cold table through direct contact. Conduction is the process of heat transfer through a material due to direct molecular collisions. Radiation (choice A) involves the transfer of heat through electromagnetic waves, which is not the primary process in this scenario. Convection within the coffee (choice C) involves the transfer of heat through the movement of fluid particles, but in this case, the primary heat transfer mechanism is conduction. Choice D is incorrect as it suggests a combination of conduction and convection, when conduction is the dominant process in this situation.

Correct Answer: A

Rationale: To calculate the magnitude of the resulting force, we use Coulomb's Law: F = k * |q1 * q2| / r^2, where k is the electrostatic constant (8.99 x 10^9 N m^2/C^2), q1 and q2 are the charges, and r is the distance between them. Plugging in the values: F = (8.99 x 10^9) * |4 x 10^-6 * 2 x 10^-6| / 1^2 = 0.072 N. However, the question asks for the magnitude, so the answer should be 0.072 N, which corresponds to choice B. The other choices are incorrect because they do not correctly calculate the force using Coulomb's Law or misinterpret the question.

Correct Answer: C

Rationale: To find the image distance using the mirror formula (1/f = 1/v + 1/u), we first need to calculate the object distance (u). Given the object distance (u) is 20 cm, and the focal length (f) is 10 cm, we can substitute these values into the formula to find the image distance (v). Solving for v, we get v = 60 cm. Therefore, the correct answer is C: 60 cm. Choice A (20 cm) is incorrect as the image distance is not equal to the object distance when using a concave mirror. Choice B (40 cm) is incorrect as it does not account for the focal length of the mirror. Choice D (75 cm) is incorrect as it is not the result of the correct calculation using the mirror formula.

Correct Answer: D

Rationale: The correct answer is D: Cannot be created or destroyed. According to the law of conservation of energy, energy can neither be created nor destroyed, but only transformed from one form to another. This principle is a fundamental law of physics known as the first law of thermodynamics. Any process involving energy transfer must adhere to this law. Choices A, B, and C are incorrect because they contradict this fundamental principle. Energy cannot be created out of nothing or disappear completely; it can only change forms.