Nursing Elites

1. What does Coulomb’s law relate to?

• A. electrostatic interaction
• B. rigid body motion
• C. heat conduction
• D. universal gravitation

Correct answer: A

Rationale: Coulomb's law is a fundamental principle in physics that deals with the electrostatic interaction between charged particles. It states that the force between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. This law is crucial in understanding and predicting the behavior of electrically charged objects. Choices B, C, and D are incorrect because Coulomb's law specifically focuses on electrostatic interactions between charges, not rigid body motion, heat conduction, or universal gravitation.

2. An object with a charge of 3 μC is placed 30 cm from another object with a charge of 2 μC. What is the magnitude of the resulting force between the objects?

• A. 0.6 N
• B. 0.18 N
• C. 180 N
• D. 9 × 10−12 N

Correct answer: B

Rationale: To find the magnitude of the resulting force between two charges, we use Coulomb's Law: F = k × (|q1 × q2|) / r² Where: F is the force k is Coulomb’s constant (8.99 × 10⁹ N·m²/C²) q1 and q2 are the charges r is the distance between the charges Plugging in the values: F = (8.99 × 10⁹) × (3 × 10⁻⁶) × (2 × 10⁻⁶) / (0.3)² = 0.18 N. Therefore, the magnitude of the resulting force is 0.18 N.

3. In a circuit with three same-size resistors wired in series to a 9-V power supply, producing 1 amp of current, what is the resistance of each resistor?

• A. 9 ohms
• B. 6 ohms
• C. 3 ohms
• D. 1 ohm

Correct answer: C

Rationale: In a series circuit, the total resistance is the sum of the individual resistances. With a total voltage of 9 V and a current of 1 A, we can use Ohm's Law (V = I × R) to find the total resistance: Total resistance = 9 V / 1 A = 9 ohms. Since the resistors are identical and wired in series, the total resistance is evenly divided among the three resistors: Resistance of each resistor = 9 ohms / 3 = 3 ohms. Thus, the resistance of each resistor is 3 ohms. Therefore, the correct answer is 3 ohms. Choice A, 9 ohms, is incorrect because this would be the total resistance of all three resistors combined in series. Choice B, 6 ohms, is incorrect as it does not account for the equal distribution of resistance in a series circuit. Choice D, 1 ohm, is incorrect as it is too low for resistors in series with a total resistance of 9 ohms.

4. A hummingbird’s wings beat at 25 beats per second. What is the period of the wing beating in seconds?

• A. 0.04 s
• B. 0.25 s
• C. 0.4 s
• D. 4 s

Correct answer: A

Rationale: The period represents the time for one complete cycle of the wing beating. To calculate the period, you take the reciprocal of the frequency. In this case, with the wings beating at 25 beats per second, the period is 1/25, which equals 0.04 seconds. Therefore, choice A, 0.04 seconds, is correct. Choices B, C, and D are incorrect because they do not reflect the correct calculation of the period based on the given frequency of 25 beats per second.

5. The Prandtl number (Pr) is a dimensionless property relating:

• A. Viscosity and thermal diffusivity
• B. Density and pressure
• C. Surface tension and pressure
• D. Reynolds number and flow regime

Correct answer: A

Rationale: The Prandtl number (Pr) is a dimensionless number used to characterize fluid flow. It is the ratio of momentum diffusivity to thermal diffusivity. In simpler terms, it relates the ability of a fluid to conduct heat to its ability to conduct momentum. Therefore, the correct relationship is between viscosity and thermal diffusivity, making choice A the correct answer. Choices B, C, and D are incorrect because they do not represent the properties that the Prandtl number relates.

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