HESI A2 Physics

Correct Answer: B

Rationale: To find the frequency, we use the formula: speed = wavelength x frequency. Given speed = 12 m/s and wavelength = 2 m, we can rearrange the formula to solve for frequency: frequency = speed / wavelength = 12 m/s / 2 m = 6 Hz. Choice A (38.4 Hz) is incorrect as it would be the frequency if the wavelength was 0.3125 m, not 2 m. Choice C (4.6 Hz) and D (3.75 Hz) are also incorrect as they do not match the calculated frequency of 6 Hz based on the given values.

Correct Answer: D

Rationale: To find the total voltage in a series circuit, you add the voltages of each battery. In this case, with four 5 V batteries connected in series, the total voltage would be 5 V + 5 V + 5 V + 5 V = 20 V. Therefore, the correct answer is D. Choice A (5.0 V) is incorrect because that would be the voltage of just one battery, not the total voltage of the circuit. Choice B (10.0 V) is incorrect as well since it represents the total voltage of two batteries, not four. Choice C (15.0 V) is also incorrect as it would be the total voltage of three batteries, not four.

Correct Answer: D

Rationale: The correct answer is D because salt increases the density of water, making it more buoyant. Higher water density provides greater buoyant force on the boat, allowing it to float more easily. Choices A, B, and C are incorrect as salt does not directly affect the mass of the boat, the volume of water, or the density of the boat itself.

Correct Answer: B

Rationale: To find the radius of the circular track, we use the formula: circumference = 2 * π * radius. Given circumference = 2,500m, we can rearrange the formula to solve for radius: radius = circumference / (2 * π) = 2,500 / (2 * 3.14) ≈ 398.73m. Therefore, the closest option to the calculated radius is B: 400m. Incorrect answers: A: 1,000m - This is twice the correct radius, not accurate. C: 25m - This is 10 times smaller than the correct radius, not accurate. D: 12m - This is much smaller than the correct radius, not accurate.

Correct Answer: A

Rationale: Surface tension is caused by the cohesive forces between molecules in a fluid, which are the intermolecular forces. These forces create an imbalance at the surface, resulting in the phenomenon of surface tension. Gravitational attraction (B) is not the primary cause of surface tension, viscous dissipation (C) is related to fluid flow resistance, and pressure differentials (D) within the fluid do not directly cause surface tension. Therefore, the correct answer is A.