HESI A2 Physics

Correct Answer: A

Rationale: The correct answer is A: Hertz. Frequency is the number of cycles per second in an alternating current (AC). Hertz is the unit used to measure frequency. It represents the number of times the current changes direction in one second. Amperes (B) measure current, Volts (C) measure voltage, and Ohms (D) measure resistance, which are not related to the frequency of an AC current.

Correct Answer: D

Rationale: The correct answer is D: Kinetic energy. Potential energy is the energy stored in an object due to its position or state. As the vehicle rolls downhill, potential energy decreases while kinetic energy, the energy of motion, increases. This transformation occurs as the vehicle gains speed and moves due to the force of gravity. The other choices are incorrect because thermal energy is not directly related to the motion of the vehicle in this scenario, and the transformation does not involve a combination of thermal and kinetic energy. The vehicle's movement downhill is primarily a conversion of potential energy into kinetic energy.

Correct Answer: B

Rationale: The correct answer is B: Newton's second law of motion. This law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. The formula for this relationship is F = ma, where F is the force applied, m is the mass of the object, and a is the acceleration produced. This equation clearly expresses the relationship between acceleration and force. Now, let's analyze why the other choices are incorrect: A: Newton's first law of motion, also known as the law of inertia, states that an object at rest will remain at rest, and an object in motion will remain in motion unless acted upon by an external force. This law does not directly relate to the relationship between acceleration and force. C: Newton's third law of motion states that for every action, there is an equal and opposite reaction. This law describes the interaction between two objects and their forces, not the relationship between acceleration and force. D: Saying

Correct Answer: B

Rationale: To determine the stretch of the spring when a 30 kg force is applied, we first calculate the spring constant using Hooke's Law: F = kx. Given F1 = 12 kg and x1 = 3 cm, k = F1/x1 = 12 kg / 0.03 m = 400 N/m. Then, for F2 = 30 kg, x2 = F2 / k = 30 kg / 400 N/m = 0.075 m = 7.5 cm. Therefore, choice B (7.5 cm) is the correct answer. Choices A, C, and D are incorrect as they do not align with the calculated value using Hooke's Law.

Correct Answer: C

Rationale: The correct answer is C because psychrometrics specifically deals with the properties of mixtures of moist air and water vapor. It focuses on the study of air-water vapor mixtures and their interactions, such as humidity, temperature, and moisture content. Choice A (Ideal gases) is incorrect because psychrometrics goes beyond the behavior of ideal gases. Choice B (Magnetic materials) is incorrect as it is unrelated to the study of air-water vapor mixtures. Choice D (Nuclear reactions) is also incorrect as it pertains to nuclear physics, not the properties of air-water vapor mixtures. In summary, the correct answer C aligns with the specific focus of psychrometrics on moist air and water vapor properties, making it the most appropriate choice.