HESI A2 Physics Practice Test

Correct Answer: B

Rationale: The correct expression for work (W) is W = F x d. Work is defined as the product of the force applied (F) in the direction of motion and the displacement (d) of the object. Multiplying force by displacement gives the total energy transferred to the object. Option A (W = F / d) is incorrect because dividing force by distance does not represent work. Option C (W = d / F) is incorrect as work is not calculated by dividing distance by force. Option D (W = F^2 x d) is incorrect as squaring the force before multiplying it by displacement is not the correct formula for work. The correct formula for work is the product of force and displacement (W = F x d).

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: A

Rationale: When a dielectric material is inserted between the plates of a charged capacitor, the capacitance will increase. This is because the dielectric reduces the electric field between the plates, which allows for more charge to be stored for a given potential difference. The dielectric polarization enhances the capacitance. The other choices are incorrect because capacitance does not decrease or remain the same when a dielectric is added, and it is not unpredictable as the relationship between capacitance and dielectric constant is well-defined.

Correct Answer: D

Rationale: Cavitation occurs when the pressure drops below the vapor pressure of the fluid, causing bubbles to form and collapse. If the pressure drops below the vapor pressure, the fluid will vaporize, leading to cavitation. Boiling point (A), density (B), and freezing point (C) are not directly related to cavitation. Boiling point is the temperature at which a liquid turns into vapor, density is the mass per unit volume of a substance, and freezing point is the temperature at which a liquid turns into a solid. Only vapor pressure (D) is directly linked to cavitation.

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.