HESI A2 Physics Practice Test

Correct Answer: D

Rationale: Step-by-step rationale: 1. In an isothermal process, temperature remains constant. 2. Compressing a gas increases its pressure. 3. Work is done on the gas by the surroundings in compression. 4. As work is done on the gas, its internal energy decreases. Therefore, choice D is correct. Summary: A: Incorrect; Internal energy does not increase when work is done on the gas. B: Incorrect; Internal energy does not decrease when work is done on the gas. C: Incorrect; Work is done by the surroundings on the gas, not vice versa.

Correct Answer: A

Rationale: The correct answer is A: H = U + PV. Enthalpy (H) is defined as H = U + PV, where U is internal energy, P is pressure, and V is volume. This equation comes from the first law of thermodynamics, which states that the change in internal energy of a system is equal to the heat added to the system minus the work done by the system. In this case, the work done by the system is PΔV, which represents the product of pressure and volume. Therefore, the correct relationship between enthalpy, internal energy, pressure, and volume is H = U + PV. Choices B, C, and D are incorrect because they do not accurately represent the definition of enthalpy. Choice B (H = U - PV) is incorrect because it subtracts the product of pressure and volume from internal energy, which is not the correct relationship. Choice C (H = U / PV) is incorrect because it divides internal

Correct Answer: D

Rationale: The surrounding air is NOT considered a part of the system when analyzing a power plant as it acts as the environment outside the system boundary. The system typically includes components directly involved in the energy conversion process, such as the fuel, working fluid, and turbine. The surrounding air, while it may have an impact on the plant's operations, is not a component within the system boundary and does not play a direct role in the energy conversion process. Choices A, B, and C are all integral parts of the power plant system as they are directly involved in the conversion of energy from the fuel to electricity.

Correct Answer: B

Rationale: Faraday's law of electromagnetic induction states that a changing magnetic field in a conductor induces an electromotive force (EMF) according to the Faraday's law equation. This induced EMF creates a current flow in the conductor. The other choices are incorrect because an increase in resistance (choice A) would oppose the current induced by the changing magnetic field, static electric charge (choice C) is not related to induction, and a decrease in capacitance (choice D) is not directly affected by a changing magnetic field.

Correct Answer: B

Rationale: To calculate the magnitude of the resulting force, we use Coulomb's Law: \(F = k \cdot \frac{{|q_1 \cdot q_2|}}{{r^2}}\), where \(k\) is the electrostatic constant, \(q_1\) and \(q_2\) are the charges, and \(r\) is the distance between them. Plugging in the values, we get \(F = 9 \times 10^9 \cdot \frac{{3 \times 10^{-6} \cdot 2 \times 10^{-6}}}{{(0.3)^2}} = 0.18\) N. Choice B is correct because it correctly calculates the force using Coulomb's Law. Choices A, C, and D are incorrect because they either miscalculate the force or provide unrealistic values that do not align with the physics of electrostatic forces.