Nursing Elites

1. In fluid dynamics, the continuity equation, a fundamental principle, expresses the conservation of:

• A. Momentum
• B. Mass
• C. Energy
• D. Angular momentum

Correct answer: B

Rationale: The continuity equation in fluid dynamics is a statement of the conservation of mass, making choice B the correct answer. It states that the mass entering a system must equal the mass leaving the system, assuming no mass is created or destroyed within the system. Conservation of momentum (choice A) is related to Newton's laws of motion and is not directly expressed by the continuity equation. Conservation of energy (choice C) involves different principles like the first law of thermodynamics and is not the focus of the continuity equation. Angular momentum (choice D) is also a different concept related to rotational motion and not described by the continuity equation.

2. The buoyant force, F_b, experienced by an object submerged in a fluid is given by:

• A. F_b = W, the object's weight
• B. F_b = W_d, the weight of the fluid displaced by the object
• C. F_b = ρ, the density of the fluid
• D. F_b = V, the object's volume

Correct answer: B

Rationale: The correct formula for the buoyant force experienced by an object submerged in a fluid is given by Archimedes' principle, which states that the buoyant force is equal to the weight of the fluid displaced by the object. This is represented by the formula F_b = W_d, where W_d is the weight of the fluid displaced by the object. This force acts in the opposite direction to gravity and is responsible for objects floating or sinking in fluids. Choice A is incorrect because the buoyant force is not equal to the object's weight. Choice C is incorrect because the density of the fluid is not directly related to the buoyant force. Choice D is incorrect because the object's volume is not the determining factor for the buoyant force.

3. A key parameter in fluid selection is specific gravity (SG). For a submerged object in a reference fluid (often water), SG = ρ_object / ρ_reference. An object with SG > 1 will:

• A. Experience a net buoyant force acting upwards
• B. Experience a net buoyant force acting downwards
• C. Remain neutrally buoyant
• D. Require knowledge of the object's volume for buoyancy determination

Correct answer: A

Rationale: When the specific gravity (SG) of an object is greater than 1, it indicates that the object is denser than the reference fluid, which is often water. According to Archimedes' principle, an object with SG > 1 will experience a net buoyant force acting upwards when submerged in the fluid. This is because the buoyant force is greater than the weight of the object, causing it to float. Therefore, the correct answer is A: 'Experience a net buoyant force acting upwards.' Objects with SG < 1 would sink as they are less dense than the fluid, while objects with SG = 1 would be neutrally buoyant, neither sinking nor floating.

4. A plucked guitar string makes 80 vibrations in one second. What is the period?

• A. 0.0125 s
• B. 0.025 s
• C. 0.125 s
• D. 0.25 s

Correct answer: B

Rationale: The period is the time taken for one complete vibration of the guitar string. To find the period, you need to take the reciprocal of the frequency. Since the string makes 80 vibrations in one second, the period is 1/80 = 0.0125 seconds (or 0.025 s). Choice A is incorrect because it is the reciprocal of 80. Choice C is incorrect as it is 10 times the reciprocal of 80. Choice D is incorrect as it is 100 times the reciprocal of 80.

5. A 110-volt appliance draws 0 amperes. How many watts of power does it require?

• A. 0 watts
• B. 108 watts
• C. 112 watts
• D. 220 watts

Correct answer: A

Rationale: When a 110-volt appliance draws 0 amperes, it means that the power consumption is zero as well. The formula to calculate power is P = V x I, where P is power in watts, V is voltage in volts, and I is current in amperes. Since the current is 0 amperes, the power required by the appliance is also 0 watts. Therefore, the correct answer is 0 watts. Choice B, 108 watts, is incorrect because there is no current drawn. Choice C, 112 watts, and choice D, 220 watts, are incorrect as well since the appliance is not consuming any power when drawing 0 amperes.

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