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: B

Rationale: The correct answer is B: Interface between the liquid and a surrounding gas. This is because in open-channel flow, the free surface is the boundary between the liquid flowing in the channel and the air above it. This interface is essential in determining the behavior of the flow, such as wave formation and surface tension effects. A: The interface between the liquid and the container walls is not the free surface in open-channel flow. C: The bottom of the channel is not the free surface, as the free surface specifically refers to the top boundary of the flowing liquid. D: The region of highest velocity within the liquid is not the free surface, as the free surface is a boundary between the liquid and the surrounding gas, not a velocity-related property.

Correct Answer: D

Rationale: Step-by-step rationale: 1. In an isothermal process, temperature remains constant. 2. Compressing a gas increases its pressure. 3. Work is done on the gas by the surroundings in compression. 4. As work is done on the gas, its internal energy decreases. Therefore, choice D is correct. Summary: A: Incorrect; Internal energy does not increase when work is done on the gas. B: Incorrect; Internal energy does not decrease when work is done on the gas. C: Incorrect; Work is done by the surroundings on the gas, not vice versa.

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 because in shear thickening behavior, the fluid's viscosity increases with increasing shear rate. As more force is applied, the fluid's particles align in a way that increases resistance to flow, leading to higher viscosity. Choices A and B are incorrect because shear thickening involves a change in viscosity with shear rate. Choice D is incorrect as viscosity in non-Newtonian fluids is influenced by shear rate, not just applied pressure.