HESI Exams Quizlet Physics

Correct Answer: C

Rationale: To find the frequency of the wave, we use the formula: speed = wavelength x frequency. Given speed = 20 m/s and wavelength = 4 m, we rearrange the formula to solve for frequency: frequency = speed / wavelength = 20 m/s / 4 m = 5 Hz. Therefore, the correct answer is C: 24 s^-1. Choice A is incorrect as it does not match the calculated frequency. Choices B and D are also incorrect as they do not align with the calculated frequency based on the given information.

Correct Answer: B

Rationale: In an isobaric process (constant pressure), work done is given by W = PΔV. Since the pressure is constant, work done is directly proportional to the volume change. As volume increases, work is done by the system, making it positive. If volume decreases, work is done on the system, making it negative. Choice A is incorrect as work is done even if volume change is zero. Choice C is incorrect as work's sign depends on the direction of volume change. Choice D is incorrect as work done is indeed dependent on pressure and volume change in an isobaric process.

Correct Answer: B

Rationale: The correct answer is B because as a raindrop falls, air resistance increases, counteracting the force of gravity. Initially, gravity pulls the raindrop down, causing it to accelerate. However, as the raindrop gains speed, air resistance becomes stronger, eventually balancing out the gravitational force. This results in a constant velocity rather than acceleration. A: Gravity does pull the raindrop down, but it doesn't do so at a constant rate. The acceleration due to gravity is constant but is countered by air resistance. C: The mass of the raindrop remains constant as it falls, so its mass decreasing is not a factor in its speed. D: Objects in motion do not necessarily decelerate over distance; in the case of the raindrop, air resistance prevents further acceleration.

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.