HESI A2 Physics Practice Test

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: 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: C

Rationale: The correct answer is C: Identical. When the crane hoists a massive object at a constant velocity, the work done is the same as lifting it gradually because work done is the force applied multiplied by the displacement in the direction of the force. Since the velocity is constant, the force applied remains constant, and the displacement is the same whether lifted gradually or at a constant velocity. Therefore, the work done is identical in both scenarios. Summary: A: Less - Incorrect. The work done is not less when hoisting a massive object at a constant velocity. B: More - Incorrect. The work done is not more when hoisting a massive object at a constant velocity. D: Dependent on the object's mass - Incorrect. The object's mass does not affect the work done in this scenario.

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.