Nursing Elites

1. When a small object floats on the surface of a liquid, the surface tension creates a:

• A. Buoyant force acting upwards
• B. Pressure difference causing sinking
• C. Drag force opposing motion
• D. Restoring force towards equilibrium

Correct answer: D

Rationale: Surface tension creates a restoring force that holds the object on the surface. The liquid's surface behaves like a stretched membrane, and when disturbed, it tends to return the object to its original position, creating a restoring force. The other choices are incorrect: A buoyant force acts on objects submerged in a fluid, not floating on the surface; pressure differences usually affect sinking objects, not floating ones; drag force is a resistance force that opposes motion, not related to surface tension.

2. When a car is driven for a long time, the pressure of air in the tires increases. This is best explained by which of the following gas laws?

• A. Boyle's law
• B. Charles' law
• C. Gay-Lussac's law
• D. Dalton's law

Correct answer: C

Rationale: Gay-Lussac's law, also known as the law of pressure-temperature, states that the pressure of a gas is directly proportional to its absolute temperature when the volume is constant. As a car is driven for a long time, the tires heat up due to friction and increased air pressure inside the tires. This results in an increase in temperature, causing the pressure of the air inside the tires to increase according to Gay-Lussac's law. Choices A, B, and D are incorrect. Boyle's law relates pressure and volume, Charles' law relates volume and temperature, and Dalton's law deals with the partial pressures of gases in a mixture.

3. When a fluid flows past a solid object, a thin layer of fluid adheres to the object's surface due to:

• A. Buoyancy
• B. Bernoulli's principle
• C. Boundary layer effect
• D. Surface tension minimization

Correct answer: C

Rationale: The boundary layer effect occurs when a thin layer of fluid near the surface of a solid adheres to it due to viscosity. This layer experiences a velocity gradient as the fluid farther from the surface moves faster, while the fluid closest to the surface is nearly stationary.

4. Fluid dynamics is a subfield of fluid mechanics concerned with:

• A. Equilibrium properties of fluids at rest (Fluid Statics)
• B. The motion and behavior of fluids under various conditions
• C. Phase transitions of fluids between liquid, gas, and solid states
• D. Engineering applications of fluids (related but broader than fluid dynamics)

Correct answer: B

Rationale: Fluid dynamics is the study of fluids in motion and their behavior under different conditions, including how they flow, mix, and interact with their surroundings. It focuses on the dynamic aspects of fluids rather than their static properties when at rest, which is the realm of fluid statics. Phase transitions of fluids between liquid, gas, and solid states are more related to thermodynamics than fluid dynamics. While engineering applications involve fluid dynamics, the field itself is more specialized in studying the movement and behavior of fluids.

5. In fluid machinery, pumps are designed to primarily increase the fluid's:

• A. Pressure
• B. Velocity only
• C. Both pressure and velocity
• D. Neither pressure nor velocity

Correct answer: A

Rationale: Pumps in fluid machinery are designed to primarily increase the fluid's pressure. This increase in pressure allows the fluid to flow through the system efficiently and overcome resistance. While pumps can also impact the velocity of the fluid to some extent, their main function is to elevate the pressure to facilitate the movement of the fluid within the system. Choice B is incorrect because pumps do not focus solely on increasing velocity. Choice C is incorrect as while pumps can affect velocity, their primary purpose is to boost pressure. Choice D is incorrect as pumps aim to increase either the pressure, velocity, or both.

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