HESI A2
HESI A2 Physics
1. 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.
2. According to the law of conservation of energy, energy:
- A. Can be created or destroyed
- B. Can be created, but not destroyed
- C. Can be destroyed, but not created
- D. Cannot be created or destroyed
Correct answer: D
Rationale: The correct answer is D: 'Cannot be created or destroyed.' The law of conservation of energy states that energy cannot be created or destroyed; it can only be transformed from one form to another. This principle is a fundamental concept in physics and is supported by numerous observations and experiments. Choices A, B, and C are incorrect because they do not align with the law of conservation of energy. Energy is a conserved quantity, meaning its total amount remains constant over time, even though it can change forms.
3. During an isothermal (constant temperature) expansion, what is the work done by the gas on the surroundings?
- A. Positive and equal to the change in internal energy.
- B. Zero.
- C. Negative and equal to the change in internal energy.
- D. Positive and greater than the change in internal energy.
Correct answer: D
Rationale: In an isothermal expansion, the temperature remains constant, meaning there is no change in internal energy. However, the gas still does work on the surroundings as it expands, and this work is positive. Since internal energy does not change, the correct answer is D, 'Positive and greater than the change in internal energy.' Choice A is incorrect because the work done is not equal to the change in internal energy. Choice B is incorrect as work is done during the expansion. Choice C is incorrect since the work done is not negative during an isothermal expansion.
4. Longitudinal waves have vibrations that move ___________.
- A. at right angles to the direction of the vibrations
- B. in the direction opposite to that of the wave
- C. in the same direction as the wave
- D. in waves and troughs
Correct answer: C
Rationale: In longitudinal waves, the vibrations of particles occur in the same direction as the wave propagates. This means the particles move back and forth in the direction of the wave, creating compressions and rarefactions along the wave. Therefore, the correct choice is C, in the same direction as the wave. Choice A is incorrect because transverse waves, not longitudinal waves, have vibrations at right angles to the direction of wave propagation. Choice B is incorrect as it describes the motion in transverse waves. Choice D is incorrect as it is an inaccurate representation of how longitudinal waves propagate.
5. Surface tension, γ, is a property of fluids arising from:
- A. Intermolecular forces between fluid molecules
- B. Gravitational attraction
- C. Viscous dissipation
- D. Pressure differentials within the fluid
Correct answer: A
Rationale: Surface tension, represented by symbol γ, is caused by the cohesive forces between molecules in a liquid. These intermolecular forces, such as Van der Waals forces, hydrogen bonding, and dipole-dipole interactions, create a 'skin' at the surface of the liquid, giving rise to the property of surface tension. Gravitational attraction, viscous dissipation, and pressure differentials within the fluid do not directly contribute to surface tension. Therefore, the correct answer is A.
Similar Questions
Access More Features
HESI A2 Basic
$99/ 30 days
- 3,000 Questions with answers
- 30 days access @ $99
HESI A2 Premium
$149.99/ 90 days
- Actual HESI A 2 Questions
- 3,000 questions with answers
- 90 days access @ $149.99