HESI Exams Quizlet Physics

Correct Answer: C

Rationale: The correct answer is C because when the car hits the ground, all of its potential energy is converted into kinetic energy. As the car falls, potential energy decreases while kinetic energy increases. Therefore, the car does not retain any potential energy when it hits the ground. Choice A is correct as the potential energy at the height can be calculated as mgh (mass x gravity x height). Choice B is correct as potential energy is converted to kinetic energy as the car falls. Choice D is incorrect as the potential energy is first converted to kinetic energy, not directly to sound energy.

Correct Answer: B

Rationale: To find the period of a wave, we use the formula: Period = 1 / Frequency. Given the frequency of 80 vibrations per second, we calculate the period as 1 / 80 = 0.025 seconds. Therefore, choice B (0.025 s) is the correct answer. Choices A, C, and D are incorrect as they do not correctly represent the period calculation based on the given frequency. Choice A (0.0125 s) is half of the correct period, choice C (0.125 s) is ten times greater, and choice D (0.25 s) is incorrect as well.

Correct Answer: C

Rationale: The correct answer is C: Its density increases. When a junked car is compacted, its volume decreases while its mass remains constant. Density is calculated as mass divided by volume, so with a decrease in volume and constant mass, the density increases. Option A is incorrect because mass remains the same. Option B is incorrect as mass does not decrease. Option D is incorrect because density is directly related to mass and volume, and in this case, volume decreases while mass stays the same, resulting in increased density.

Correct Answer: A

Rationale: When you double the distance between two objects, the gravitational force between them decreases by a factor of 4 (inverse square law). So, if the original force was 12 units, when you double the distance, the new force will be 12/4 = 3 units. Therefore, the correct answer is A: 3 units. Summary: - Choice A (3 units) is correct as the force decreases by a factor of 4 when the distance is doubled. - Choices B (6 units), C (24 units), and D (48 units) are incorrect as they do not consider the inverse square law of gravitational force.

Correct Answer: A

Rationale: Semiconductors fall between conductors and insulators in terms of electrical conductivity because they have conductivity levels higher than insulators but lower than conductors. Conductors have high conductivity due to abundant free electrons, while insulators have very low conductivity due to the lack of free electrons. Semiconductors can conduct electricity under certain conditions by manipulating the number of free electrons through doping or applying electric fields. Therefore, choice A is correct. Choices B, C, and D are incorrect because they do not accurately represent the conductivity levels of semiconductors in relation to other materials.