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: 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: 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: 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: 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.