Nursing Elites

1. Two objects attract each other with a gravitational force of 12 units. If the distance between them is halved, what is the new force of attraction between the two objects?

• A. 3 units
• B. 6 units
• C. 24 units
• D. 48 units

Correct answer: C

Rationale: The gravitational force between two objects is inversely proportional to the square of the distance between them. When the distance is halved, the new force of attraction will be 12 units x (1/(0.5)^2) = 12 units x 4 = 24 units. Therefore, the correct answer is C. Choice A and B are incorrect as they do not consider the inverse square law of gravitational force. Choice D is incorrect as reducing the distance between the objects does not lead to a squared increase in force.

2. Certain non-Newtonian fluids exhibit shear thickening behavior. In this case, the fluid's viscosity:

• A. Remains constant with increasing shear rate
• B. Decreases with increasing shear rate (shear thinning)
• C. Increases with increasing shear rate
• D. Depends solely on the applied pressure

Correct answer: C

Rationale: When a non-Newtonian fluid exhibits shear thickening behavior, its viscosity increases with increasing shear rate. This means that as more force is applied to the fluid, its resistance to flow also increases, resulting in a higher viscosity. This phenomenon is opposite to shear thinning, where viscosity decreases with increasing shear rate. Therefore, in the case of shear thickening behavior, the correct answer is that the fluid's viscosity increases with increasing shear rate. Choices A, B, and D are incorrect because shear thickening behavior specifically involves an increase in viscosity with increasing shear rate, not remaining constant, decreasing, or depending on applied pressure.

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. 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.

5. For steady, incompressible flow through a pipe, the mass flow rate (ṁ) is related to the fluid density (ρ), cross-sectional area (A), and average velocity (v) via the continuity equation:

• A. ṁ cannot be determined without additional information
• B. ṁ = ρvA
• C. Bernoulli's principle is solely applicable here
• D. The equation of state for the specific fluid is required

Correct answer: B

Rationale: The continuity equation for steady, incompressible flow states that the mass flow rate is the product of the fluid's density, velocity, and cross-sectional area. Hence, ṁ = ρvA. Choice A is incorrect because the mass flow rate can be determined using the given formula. Choice C is incorrect as Bernoulli's principle does not directly relate to the mass flow rate calculation. Choice D is incorrect as the equation of state is not needed to calculate the mass flow rate in this scenario.

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