HESI A2
HESI A2 Physics Practice Test
1. If the force acting on an object is doubled, how does its acceleration change?
- A. It remains the same.
- B. It is halved.
- C. It is doubled.
- D. It is eliminated.
Correct answer: C
Rationale: According to Newton's second law of motion, the acceleration of an object is directly proportional to the force acting on it. Therefore, if the force acting on an object is doubled, its acceleration will also double. This relationship is expressed by the equation F = ma, where F is the force, m is the mass of the object, and a is the acceleration. When the force (F) is doubled, the acceleration (a) will also double, assuming the mass remains constant. Choice A is incorrect because acceleration changes with a change in force. Choice B is incorrect because acceleration and force are directly proportional. Choice D is incorrect because increasing the force acting on an object does not eliminate its acceleration; instead, it results in an increase in acceleration, as per Newton's second law.
2. When analyzing a power plant, which of the following is NOT considered a part of the system?
- A. The fuel being burned.
- B. The working fluid (e.g., steam or water).
- C. The turbine that generates electricity.
- D. The surrounding air.
Correct answer: D
Rationale: In a power plant system, the components directly involved in the energy conversion process are considered part of the system. The fuel being burned provides the heat source, the working fluid transfers this heat energy, and the turbine converts it into mechanical energy to generate electricity. The surrounding air, while it may interact with the system, is not a component that directly participates in the energy conversion process within the power plant system. Therefore, the correct answer is D - The surrounding air. Choices A, B, and C are essential components of a power plant system as they play direct roles in the energy conversion process, unlike the surrounding air.
3. What characterizes laminar flow?
- A. Smooth, parallel layers of fluid particles
- B. Erratic and turbulent motion of fluid particles
- C. High viscosity hindering flow
- D. Incompressibility of the fluid
Correct answer: A
Rationale: Laminar flow is characterized by the smooth, parallel movement of fluid particles along layers in a predictable manner. This flow regime occurs at low velocities and is in contrast to turbulent flow, where fluid particles exhibit erratic and chaotic motion. The viscosity of the fluid does not hinder laminar flow; instead, it influences the resistance to flow. Incompressibility is a property of fluids but does not specifically define laminar flow. Therefore, the correct answer is A as it accurately describes the behavior of fluid particles in laminar flow, making B, C, and D incorrect.
4. A 5-kg block is suspended from a spring, causing the spring to stretch 10 cm from equilibrium. What is the spring constant for this spring?
- A. 4.9 N/cm
- B. 9.8 N/cm
- C. 49 N/cm
- D. 50 N/cm
Correct answer: C
Rationale: The spring constant (k) can be calculated using Hooke's Law formula: F = -kx, where F is the force applied, k is the spring constant, and x is the displacement from equilibrium. In this case, the force applied is equal to the weight of the block, F = mg, where m = mass of the block = 5 kg and g = acceleration due to gravity = 9.8 m/s^2. The displacement x = 10 cm = 0.1 m. Substituting the values, we have: 5 kg * 9.8 m/s^2 = k * 0.1 m. Solving for k gives k = 5 * 9.8 / 0.1 = 49 N/m. Therefore, the spring constant for this spring is 49 N/cm. Choice A (4.9 N/cm) is incorrect because it is one decimal place lower than the correct answer. Choice B (9.8 N/cm) is incorrect as it does not account for the correct calculation based on the given information. Choice D (50 N/cm) is incorrect because it is slightly higher than the accurate value obtained through the calculations.
5. As a vehicle positioned at the peak of a hill rolls downhill, its potential energy transforms into:
- A. Thermal energy
- B. Neither thermal nor kinetic energy
- C. A combination of thermal and kinetic energy
- D. Kinetic energy
Correct answer: D
Rationale: The correct answer is D: Kinetic energy. Potential energy is converted into kinetic energy as the vehicle moves downhill. Kinetic energy is the energy possessed by a moving object. Thermal energy is not produced in this scenario because the energy transformation is mainly from potential to kinetic energy, not involving heat generation. Choices A, B, and C are incorrect because the primary energy transformation in this scenario is from potential to kinetic energy, not involving thermal energy.
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