HESI A2 Physics

Correct Answer: C

Rationale: The correct answer is C because when the box falls, it converts its potential energy (due to its height above the floor) into kinetic energy (due to its motion). As it falls, its potential energy decreases while its kinetic energy increases. Therefore, the box has both kinetic and potential energy after it falls. A is incorrect because the box still has kinetic energy after hitting the floor. B is incorrect because the box gains kinetic energy as it falls. D is incorrect because the box retains some kinetic energy even after hitting the floor.

Correct Answer: D

Rationale: To calculate impulse, we use the formula Impulse = Change in Momentum. First, calculate the initial momentum: initial momentum = 10 kg * 5 m/s = 50 kg⋅m/s. Then, calculate the final momentum: final momentum = 10 kg * 15 m/s = 150 kg⋅m/s. The change in momentum is final momentum - initial momentum = 150 kg⋅m/s - 50 kg⋅m/s = 100 kg⋅m/s. Therefore, the impulse applied to the object is 100 kg⋅m/s. Choice D is correct as it correctly represents the impulse value. Choices A, B, and C are incorrect as they do not accurately reflect the calculated impulse value.

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: A

Rationale: The correct answer is A: Experience a net buoyant force acting upwards. When the specific gravity of an object is greater than 1, it means the object is denser than the reference fluid. According to Archimedes' Principle, a submerged object experiences an upward buoyant force equal to the weight of the fluid it displaces. Since the object is denser than the fluid, it will displace less fluid, resulting in a net buoyant force acting upwards. Choice B is incorrect because a denser object will displace less fluid, leading to an upward buoyant force. Choice C is incorrect because neutrally buoyant objects have an SG equal to that of the reference fluid. Choice D is incorrect because the object's volume is not needed to determine the direction of the buoyant force based on specific gravity alone.

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.