HESI A2 Physics Practice Test

Correct Answer: B

Rationale: The correct answer is B: Cork. Density is mass per unit volume. Cork is the lightest material among the choices due to its low mass and high volume, resulting in the lowest density. Water (A) has a higher density than cork. Aluminum (C) and steel (D) are metals with higher densities than cork due to their higher mass and lower volume. Cork's low density makes it less dense compared to the other materials.

Correct Answer: C

Rationale: The correct answer is C (3 ohms) because in a series circuit, the total resistance is the sum of individual resistances. Since the circuit has 3 same-size resistors, each resistor must have the same resistance. Therefore, the total resistance of the circuit is 3 times the resistance of one resistor. Using Ohm's Law (V = IR), with V = 9V and I = 1A, we can find the total resistance (R) as 9V = 1A * R. Thus, R = 9 ohms for the whole circuit. Since each resistor has the same resistance, each resistor must be 1/3 of the total resistance, which is 3 ohms. Choice A (9 ohms) is incorrect because it represents the total resistance of the circuit, not the resistance of each individual resistor. Choice B (6 ohms) is incorrect because it does not consider the equal division of resistance among the three resistors

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.

Correct Answer: D

Rationale: The correct answer is D. Electrons complete a cycle 60 times per second in a 60 Hz household alternating current. This is because the frequency of AC refers to the number of complete cycles per second. Electrons moving back and forth create the alternating current flow. A: Incorrect. The power rating of a bulb (in watts) is determined by the voltage and current, not the frequency. B: Incorrect. The current in household circuits is typically much lower than 60 amperes for safety reasons. C: Incorrect. Voltage drop is dependent on the resistance in the wire and the current flowing, not the frequency of the current.

Correct Answer: B

Rationale: The correct answer is B: The ratio of the potential difference between the ends of a conductor to current is a constant, R. This is in accordance with Ohm's law, which states that V (voltage) = I (current) x R (resistance). Ohm's law establishes a direct proportionality between voltage and current when resistance is constant. The constant R represents the resistance of the conductor. Option A is incorrect because voltage and current are directly proportional when resistance is constant, not inversely proportional. Option C is incorrect as voltage is not the amount of charge passing through a point per second, but rather the potential difference. Option D is incorrect as power is calculated using the formula P = VI, not I x V.