HESI A2 Physics Practice Test

Correct Answer: D

Rationale: The correct answer is D. Electrons complete a cycle 60 times per second in a 60 Hz household alternating current. This is because the frequency of AC refers to the number of complete cycles per second. Electrons moving back and forth create the alternating current flow. A: Incorrect. The power rating of a bulb (in watts) is determined by the voltage and current, not the frequency. B: Incorrect. The current in household circuits is typically much lower than 60 amperes for safety reasons. C: Incorrect. Voltage drop is dependent on the resistance in the wire and the current flowing, not the frequency of the current.

Correct Answer: D

Rationale: Cavitation occurs when the pressure drops below the vapor pressure of the fluid, causing bubbles to form and collapse. If the pressure drops below the vapor pressure, the fluid will vaporize, leading to cavitation. Boiling point (A), density (B), and freezing point (C) are not directly related to cavitation. Boiling point is the temperature at which a liquid turns into vapor, density is the mass per unit volume of a substance, and freezing point is the temperature at which a liquid turns into a solid. Only vapor pressure (D) is directly linked to cavitation.

Correct Answer: C

Rationale: The gravitational force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them (F = G * (m1 * m2) / r^2). When the distance is halved, the force quadruples (2^2 = 4 times). Therefore, if the original force is 12 units, when the distance is halved, the new force will be 12 * 4 = 48 units. Therefore, the correct answer is C. Choice A (3 units) is incorrect because the force increases when the distance is halved. Choice B (6 units) is incorrect as well, as the force should increase more when the distance is halved. Choice D (48 units) is incorrect because the new force of attraction is not doubled but quadrupled when the distance is halved.

Correct Answer: A

Rationale: The correct answer is A: Mass. Mass is an intrinsic property of a substance that remains constant regardless of temperature changes. This is because mass is a measure of the amount of matter in an object and does not depend on external factors like temperature. Volume (B) can change with temperature as substances expand or contract. Phase (C) can change with temperature shifts, such as from solid to liquid or gas. Solubility (D) can also be influenced by temperature, as it affects how well a substance dissolves in a solvent. Therefore, mass is the only property that remains constant regardless of temperature variations.

Correct Answer: D

Rationale: The correct answer is D (5 feet). When Jack stands 5 feet away from the mirror, his image will appear the same distance behind the mirror. This is because the distance between Jack and his image in the mirror is equal to the distance between Jack and the mirror itself. Therefore, the image of Jack will also be 5 feet away from him. Choice A (2.5 feet) is incorrect because the image distance is equal to the object distance in a plane mirror. Choice B (3 feet) is incorrect as it does not follow the principle of image formation in a plane mirror. Choice C (4.5 feet) is incorrect as the image distance is always equal to the object distance in a plane mirror.