Nursing Elites

1. The drag force (F_d) experienced by an object moving through a fluid depends on:

• A. Object's shape and size only
• B. Fluid properties and object velocity
• C. Depth of submersion only
• D. Buoyant force acting on the object

Correct answer: B

Rationale: The drag force experienced by an object moving through a fluid depends on multiple factors, including the object's shape, size, velocity, and the fluid's properties such as viscosity and density. Choices A, C, and D are incorrect because drag force is not solely determined by the object's shape and size, depth of submersion, or buoyant force acting on the object. The primary factors affecting drag force are the fluid properties and the object's velocity. Therefore, the correct answer is B.

2. Cavitation is a phenomenon observed in fluids when the pressure falls below its:

• A. Boiling point
• B. Density
• C. Freezing point
• D. Vapor pressure

Correct answer: D

Rationale: Cavitation is a phenomenon where vapor bubbles form in a fluid due to pressure dropping below the vapor pressure of the liquid. When this occurs, the bubbles collapse, creating intense shock waves. The pressure falling below the vapor pressure is what triggers cavitation, not the boiling point, density, or freezing point of the fluid. Therefore, the correct answer is 'Vapor pressure,' as it directly relates to the pressure threshold required for cavitation to happen.

3. The first law of thermodynamics is a principle of energy conservation. It states that:

• A. Energy can be created or destroyed.
• B. The total entropy of an isolated system always decreases.
• C. Energy can neither be created nor destroyed, only transferred or transformed.
• D. The temperature of a system is directly proportional to its entropy.

Correct answer: C

Rationale: The first law of thermodynamics states that energy cannot be created or destroyed; it can only be transferred or converted from one form to another, ensuring energy conservation in any system. Choice A is incorrect because it goes against the principle of energy conservation. Choice B is incorrect as it refers to the second law of thermodynamics, which states that the total entropy of an isolated system always increases. Choice D is incorrect because the temperature of a system is not directly proportional to its entropy.

4. The efficiency (η) of a heat engine is defined as the ratio of the net work done (Wnet) by the engine to the heat input (Qh) from the hot reservoir. The relationship is expressed as:

• A. η = Wnet / Qh
• B. η = Qh / Wnet
• C. η = Wnet x Qh
• D. η = (Wnet + Qh) / 2

Correct answer: A

Rationale: The correct formula for efficiency (η) of a heat engine is η = Wnet / Qh. Efficiency is defined as the ratio of the net work done by the engine (Wnet) to the heat input from the hot reservoir (Qh). This formula shows how effectively the engine converts heat into useful work, making choice A the correct answer. Choices B, C, and D present incorrect relationships between efficiency, net work done, and heat input, leading to their incorrectness.

5. The frequency of an alternating current (AC) refers to the number of times it changes direction per unit time. This is measured in:

• A. Hertz
• B. Amperes
• C. Volts
• D. Ohms

Correct answer: A

Rationale: The frequency of an alternating current (AC) is measured in Hertz (Hz), which denotes the number of times the current changes direction per unit time. Hertz is the unit for frequency, while amperes measure current, volts measure voltage, and ohms measure resistance. Therefore, the correct answer is Hertz (Hz). Choices B, C, and D are incorrect because amperes measure current intensity, volts measure voltage potential, and ohms measure resistance, not the frequency of an alternating current.

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