Nursing Elites

1. An object with a charge of 4 μC is placed 50 cm from another object with a charge twice as great. What is the magnitude of the resulting repulsive force?

• A. 0.1152 N
• B. 1.152 N
• C. 10^−3 N
• D. 2.5 × 10^−3 N

Correct answer: D

Rationale: The force between two charges is calculated using Coulomb's Law, which states that the force is proportional to the product of the two charges and inversely proportional to the square of the distance between them. Given that one charge is twice as great as the other and the distance between them is 50 cm, we can calculate the repulsive force. The magnitude of the resulting repulsive force is 2.5 × 10^−3 N. Choice A is incorrect as it does not match the calculated value. Choice B is incorrect as it is significantly higher than the correct answer. Choice C is incorrect as it represents 10^−3 N, which is lower than the calculated value.

2. For a compressible fluid subjected to rapid pressure changes, sound wave propagation becomes important. The speed of sound (c) depends on the fluid's:

• A. Density (ρ) only
• B. Viscosity (μ) only
• C. Density (ρ) and Bulk modulus
• D. Density (ρ) and Surface tension (γ)

Correct answer: C

Rationale: In a compressible fluid, the speed of sound (c) depends on both the fluid's density (ρ) and Bulk modulus. Density affects the compressibility of the fluid, while Bulk modulus represents the fluid's resistance to compression and plays a crucial role in determining the speed of sound in a compressible medium. Viscosity and surface tension do not directly impact the speed of sound in a compressible fluid subjected to rapid pressure changes. Therefore, the correct answer is C.

3. If a wave has a frequency of 60 hertz, which of the following is true?

• A. It completes one cycle per minute.
• B. It measures 60 m from crest to crest.
• C. It completes 60 cycles per second.
• D. It measures 60 m from crest to trough.

Correct answer: C

Rationale: The frequency of a wave is the number of cycles it completes in one second. A wave with a frequency of 60 hertz completes 60 cycles per second. Therefore, choice C is correct. Choice A is incorrect because a frequency of 60 hertz means 60 cycles per second, not per minute. Choice B is incorrect as the frequency of the wave does not determine the distance from crest to crest. Choice D is also incorrect as the frequency does not relate to the distance from crest to trough.

4. Enthalpy (H) is a thermodynamic property defined as the sum of a system's internal energy (U) and the product of its pressure (P) and volume (V). The relationship between these is:

• A. H = U + PV
• B. H = U - PV
• C. H = U / PV
• D. H = PV / U

Correct answer: A

Rationale: Enthalpy (H) is defined as H = U + PV, where U represents internal energy, P is pressure, and V is volume. Enthalpy includes both the internal energy of a system and the energy required to create space for the system against an external pressure. Therefore, the correct relationship between enthalpy, internal energy, pressure, and volume is H = U + PV. Choice B is incorrect as subtracting PV would not account for the work done against pressure. Choice C is incorrect as dividing U by PV doesn't represent the definition of enthalpy. Choice D is incorrect as dividing PV by U is not the correct relationship based on the definition of enthalpy.

5. 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.

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