HESI A2 Physics

Correct Answer: A

Rationale: To calculate the magnitude of the resulting force, we use Coulomb's Law: F = k * |q1 * q2| / r^2, where k is the electrostatic constant (8.99 x 10^9 N m^2/C^2), q1 and q2 are the charges, and r is the distance between them. Plugging in the values: F = (8.99 x 10^9) * |4 x 10^-6 * 2 x 10^-6| / 1^2 = 0.072 N. However, the question asks for the magnitude, so the answer should be 0.072 N, which corresponds to choice B. The other choices are incorrect because they do not correctly calculate the force using Coulomb's Law or misinterpret the question.

Correct Answer: A

Rationale: The correct answer is A: 5 miles per hour due southwest. A vector quantity has both magnitude and direction, which is represented by the speed (5 miles per hour) and the direction (southwest). This choice clearly indicates both aspects. Explanation for why the other choices are incorrect: - B: 5 miles per hour: This choice only provides the magnitude of the quantity (speed) without indicating any direction. - C: 5 miles: This choice only provides the magnitude (distance) without any indication of direction. - D: None of the above: This choice dismisses all options without providing the correct representation of a vector quantity with both magnitude and direction.

Correct Answer: A

Rationale: In an adiabatic process, there is no heat transfer between the system and the surroundings (choice A is correct). This is because adiabatic processes occur without any heat exchange, so the heat transfer (Q) is zero. The other choices are incorrect because in an adiabatic process, there is no requirement for constant temperature (choice B), constant pressure (choice C), or no change in internal energy (choice D). Adiabatic processes focus on the absence of heat transfer, not necessarily on the maintenance of specific temperature, pressure, or energy conditions.

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: During an isothermal expansion, the temperature remains constant, so the internal energy of the gas remains the same. As the gas expands, it does work on the surroundings. Work done is given by W = -PΔV, where P is pressure and ΔV is change in volume. Since the gas is doing work on the surroundings, the work done is positive. The work done is greater than the change in internal energy because some of the work is used to overcome the external pressure to expand and only a portion contributes to the change in internal energy. Therefore, choice D is correct. Choices A and C are incorrect because the work done is not equal to the change in internal energy. Choice B is incorrect because work is being done during the expansion.