HESI A2 Physics Practice Test

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: 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: The correct answer is B: Boundary layer separation. When a fluid encounters a bluff body, such as a car, the flow separates behind the object due to pressure differences, creating a region of low pressure. This separation of the boundary layer results in increased drag on the object. Cavitation (A) is the formation of vapor bubbles due to low pressure, not specific to bluff bodies. The Bernoulli effect (C) refers to the relationship between fluid speed and pressure, not directly related to flow separation. Drag crisis (D) is a sudden decrease in drag experienced by an object at high speeds, not directly related to flow separation behind a bluff body.

Correct Answer: A

Rationale: To determine the new length when the force is doubled, we can use Hooke's Law: F = kx, where F is the force, k is the spring constant, and x is the extension. First, calculate the spring constant k = F / x = 12 N / 3 cm = 4 N/cm. Then, find the new extension x' when the force is doubled (24 N): x' = F / k = 24 N / 4 N/cm = 6 cm. Therefore, the new length of the spring would be 25 cm + 6 cm = 31 cm (Choice A). The other choices are incorrect because they do not consider the linear relationship between force and extension as described by Hooke's Law.

Correct Answer: D

Rationale: Failed to generate a rationale after 5 retries.