Nursing Elites

1. Capillarity describes the tendency of fluids to rise or fall in narrow tubes. This phenomenon arises from the interplay of:

• A. Buoyancy and pressure differentials
• B. Density variations and compressibility of the fluid
• C. Viscous dissipation and inertial effects
• D. Surface tension at the liquid-gas interface and intermolecular forces

Correct answer: D

Rationale: Capillarity occurs due to surface tension and intermolecular forces between the liquid and the walls of the narrow tube. These forces cause the liquid to rise or fall depending on the cohesion and adhesion properties. Surface tension at the liquid-gas interface and intermolecular forces are responsible for capillary action, making choice D the correct answer. Choices A, B, and C are incorrect as they do not directly relate to the specific forces involved in capillarity.

2. A concave mirror with a focal length of 2 cm forms a real image of an object at an image distance of 6 cm. What is the object's distance from the mirror?

• A. 3 cm
• B. 6 cm
• C. 12 cm
• D. 30 cm

Correct answer: B

Rationale: The mirror formula, 1/f = 1/do + 1/di, can be used to solve for the object distance. Given that the focal length (f) is 2 cm and the image distance (di) is 6 cm, we can substitute these values into the formula to find the object distance. Plugging in f = 2 cm and di = 6 cm into the formula gives us 1/2 = 1/do + 1/6. Solving for do, we get do = 6 cm. Therefore, the object's distance from the mirror is 6 cm. Choice A (3 cm), Choice C (12 cm), and Choice D (30 cm) are incorrect distances as the correct object distance is determined to be 6 cm.

3. An electromagnet is holding a 1,500-kg car at a height of 25 m above the ground. The magnet then experiences a power outage, and the car falls to the ground. Which of the following is false?

• A. The car had a potential energy of 367.5 kJ.
• B. 367.5 kJ of potential energy is converted to kinetic energy.
• C. The car retains potential energy of 367.5 kJ when it hits the ground.
• D. The car’s potential energy converts to kinetic energy and then to sound energy.

Correct answer: C

Rationale: When the car falls to the ground, its potential energy is converted to kinetic energy as it accelerates downwards. Upon impact with the ground, the car's kinetic energy is dissipated in various forms, such as sound energy, heat, and deformation energy. Therefore, the car does not retain its initial potential energy of 367.5 kJ when it hits the ground. Choice A is true because the potential energy of the car can be calculated as mgh = 1500 kg * 9.8 m/s^2 * 25 m = 367,500 J = 367.5 kJ. Choice B is true because as the car falls, its potential energy is converted to kinetic energy. Choice D is true as the kinetic energy is eventually dissipated into other forms upon impact.

4. If a 5-kg ball is moving at 5 m/s, what is its momentum?

• A. 10 kgâ‹…m/s
• B. 16.2 km/h
• C. 24.75 kgâ‹…m/s
• D. 25 kgâ‹…m/s

Correct answer: D

Rationale: The momentum of an object is calculated by multiplying its mass by its velocity. In this case, the mass of the ball is 5 kg and its velocity is 5 m/s. Therefore, the momentum of the ball is 5 kg × 5 m/s = 25 kg⋅m/s. Choice A (10 kg⋅m/s) is incorrect as it does not account for both mass and velocity. Choice B (16.2 km/h) is incorrect as it provides a speed in a different unit without considering mass. Choice C (24.75 kg⋅m/s) is incorrect as it does not correctly calculate the momentum based on the given mass and velocity.

5. When analyzing a power plant, which of the following is NOT considered a part of the system?

• A. The fuel being burned.
• B. The working fluid (e.g., steam or water).
• C. The turbine that generates electricity.
• D. The surrounding air.

Correct answer: D

Rationale: In a power plant system, the components directly involved in the energy conversion process are considered part of the system. The fuel being burned provides the heat source, the working fluid transfers this heat energy, and the turbine converts it into mechanical energy to generate electricity. The surrounding air, while it may interact with the system, is not a component that directly participates in the energy conversion process within the power plant system. Therefore, the correct answer is D - The surrounding air. Choices A, B, and C are essential components of a power plant system as they play direct roles in the energy conversion process, unlike the surrounding air.

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