HESI A2 Physics Practice Test

Correct Answer: C

Rationale: The correct answer is C: 1,500 N. Net force is the sum of all forces acting on an object. In this case, if a car is experiencing a forward force of 2,000 N and a backward force of 500 N, the net force would be 2,000 N - 500 N = 1,500 N acting in the forward direction. Choice A, B, and D are incorrect because they do not consider the direction and magnitude of the forces acting on the car. A and B are too low, while D is too high. By calculating the net force as the vector sum of all forces, we find that the correct answer is C.

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: 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: Rationale: 1. Atoms are electrically neutral, meaning they have no overall charge. 2. Electrons are negatively charged, and protons are positively charged. 3. In a neutral atom, the number of protons equals the number of electrons to balance charges. 4. Therefore, in an electrically neutral atom, the number of electrons is equal to the number of protons (Choice A). Summary: - Choice B is incorrect because protons are not always equal to neutrons in an atom. - Choice C is incorrect as the number of neutrons can vary and is not always greater than protons. - Choice D is incorrect as electrons can be equal to or greater than protons in an atom, depending on the element.

Correct Answer: A

Rationale: To find the period, we use the formula: Period = 1 / Frequency. Given the frequency as 25 beats per second, we calculate 1 / 25 = 0.04 seconds. Therefore, the correct answer is A. Choice B (0.25 s) is incorrect as it represents the inverse of the frequency, not the period. Choice C (0.4 s) and D (4 s) are also incorrect as they are not the correct calculations based on the given frequency.