Nursing Elites

1. 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.

2. In terms of electrical conductivity, semiconductors fall between

• A. Conductors and insulators
• B. Conductors and superconductors
• C. Insulators and dielectrics
• D. Superconductors and insulators

Correct answer: A

Rationale: Semiconductors have electrical conductivities that lie between those of conductors (high conductivity) and insulators (low conductivity). This positioning makes choice A, 'Conductors and insulators,' the correct answer. Choice B, 'Conductors and superconductors,' is incorrect because superconductors have perfect conductivity, not intermediate like semiconductors. Choice C, 'Insulators and dielectrics,' is incorrect because dielectrics are a type of insulator, so it doesn't show the progression from high to low conductivity. Choice D, 'Superconductors and insulators,' is incorrect because superconductors have the highest conductivity, opposite to the role of semiconductors.

3. Two balloons with charges of 5 μC each are placed 25 cm apart. What is the magnitude of the resulting repulsive force between them?

• A. 0.18 N
• B. 1.8 N
• C. 10−3 N
• D. 5 × 10−3 N

Correct answer: B

Rationale: To find the repulsive force between the two charges, we use Coulomb's law: F = k(q1 * q2) / r^2. Here, k is the Coulomb constant (8.99 x 10^9 Nm^2/C^2), q1 and q2 are the charges (5 μC each), and r is the distance between the charges (25 cm = 0.25 m). Substituting these values into the formula: F = (8.99 x 10^9 Nm^2/C^2)(5 x 10^-6 C)(5 x 10^-6 C) / (0.25 m)^2. Calculating this gives F = 1.8 N. Therefore, the magnitude of the resulting repulsive force between the two balloons is 1.8 N. Choice A, C, and D are incorrect as they do not correctly calculate the force using Coulomb's law.

4. In Einstein’s mass-energy equation, what is represented by c?

• A. Distance in centimeters
• B. The speed of light
• C. Degrees Celsius
• D. Centrifugal force

Correct answer: B

Rationale: In Einstein's mass-energy equation, E=mc^2, the symbol 'c' represents the speed of light in a vacuum, which is approximately equal to 3.00 x 10^8 meters per second. This equation demonstrates the equivalence of energy (E) and mass (m) and is a fundamental concept in the theory of relativity. Choice A is incorrect as 'c' does not represent distance in centimeters. Choice C is incorrect as 'c' does not represent degrees Celsius. Choice D is incorrect as 'c' does not represent centrifugal force.

5. A spring has a spring constant of 20 N/m. How much force is needed to compress the spring from 40 cm to 30 cm?

• A. 200 N
• B. 80 N
• C. 5 N
• D. 2 N

Correct answer: D

Rationale: The change in length of the spring is 40 cm - 30 cm = 10 cm = 0.10 m. The force required to compress or stretch a spring is given by Hooke's Law: F = k × x, where F is the force, k is the spring constant (20 N/m in this case), and x is the change in length (0.10 m). Substituting the values into the formula: F = 20 N/m × 0.10 m = 2 N. Therefore, the correct answer is 2 N. Choice A (200 N) is incorrect because it miscalculates the force. Choice B (80 N) is incorrect as it does not apply Hooke's Law correctly. Choice C (5 N) is incorrect as it underestimates the force required.

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