Nursing Elites

1. A 25-cm spring stretches to 28 cm when a force of 12 N is applied. What would its length be if that force were doubled?

• A. 31 cm
• B. 40 cm
• C. 50 cm
• D. 56 cm

Correct answer: A

Rationale: When the 12 N force stretches the spring from 25 cm to 28 cm, it causes a length increase of 28 cm - 25 cm = 3 cm. Therefore, each newton of applied force causes an extension of 3 cm / 12 N = 0.25 cm/N. If the force is doubled to 24 N, the spring would extend by 24 N × 0.25 cm/N = 6 cm more than its original length of 25 cm. Thus, the new length of the spring would be 25 cm + 6 cm = 31 cm. Choice A, 31 cm, is the correct answer as calculated. Choices B, C, and D are incorrect as they do not consider the relationship between force and extension in the spring, leading to incorrect calculations of the new length.

2. Power (P) represents the rate of work done. Which formula accurately depicts power?

• A. P = W / F
• B. P = d / t
• C. P = W x t
• D. P = F / t

Correct answer: D

Rationale: Power (P) is defined as the rate of work done over time. The correct formula for power is P = W/t, where W is the work done, and t is the time taken. Therefore, option D, P = F / t, correctly represents power as work divided by time. Option A, P = W / F, is incorrect as it represents work divided by force, not power. Option B, P = d / t, is incorrect as it represents distance divided by time, not power. Option C, P = W x t, is incorrect as it represents work multiplied by time, not power. It's important to understand the distinction between work, power, force, time, and other related concepts to solve physics problems accurately.

3. Psychrometrics is a branch of thermodynamics that deals with the properties of:

• A. Ideal gases.
• B. Magnetic materials.
• C. Mixtures of moist air and water vapor.
• D. Nuclear reactions.

Correct answer: C

Rationale: Psychrometrics is the study of the physical and thermodynamic properties of gas-vapor mixtures, especially mixtures of moist air and water vapor. This branch of thermodynamics focuses on the relationships between temperature, pressure, humidity, and other properties of these mixtures. Choice A, ideal gases, is incorrect because psychrometrics specifically deals with gas-vapor mixtures, not ideal gases. Choice B, magnetic materials, and Choice D, nuclear reactions, are unrelated to psychrometrics and thermodynamics, making them incorrect. Understanding psychrometrics is crucial in fields like heating, ventilation, air conditioning, and refrigeration (HVAC&R) to design systems that effectively control air quality, comfort, and temperature.

4. Which object below has the same density?

• A. A block with a mass of 6.5 grams and a volume of 16.25 cm3
• B. A block with a mass of 80 grams and a volume of 32 cm3
• C. A block with a mass of 48 grams and a volume of 22 cm3
• D. A block with a mass of 100 grams and a volume of 250 cm3

Correct answer: A

Rationale: Density is calculated by dividing the mass of an object by its volume. The density of object A is 6.5 g / 16.25 cm3 = 0.4 g/cm3. The density of object B is 80 g / 32 cm3 = 2.5 g/cm3. The density of object C is 48 g / 22 cm3 = 2.18 g/cm3. The density of object D is 100 g / 250 cm3 = 0.4 g/cm3. Objects A and D have the same density of 0.4 g/cm3. Therefore, the correct answer is A as it has the same density as object D, making them the only objects with a density of 0.4 g/cm3.

5. Which of the following materials has the lowest density?

• A. Water
• B. Cork
• C. Aluminum
• D. Steel

Correct answer: B

Rationale: Cork has the lowest density among the given options. Cork is a lightweight material derived from the bark of cork oak trees and is known for its low density, making it float on water. Water, aluminum, and steel have higher densities compared to cork. Water is denser than cork because it has a consistent density of 1 g/cm³. Aluminum and steel are metals with much higher densities due to their atomic structures, making them denser than cork.

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