Nursing Elites

1. When a junked car is compacted, which statement is true?

• A. Its mass increases.
• B. Its mass decreases.
• C. Its density increases.
• D. Its density decreases.

Correct answer: C

Rationale: When a junked car is compacted, its volume decreases while its mass remains the same. As a result, the car's density increases because density is mass divided by volume. Choice A is incorrect because the mass of the car remains the same. Choice B is incorrect because the mass does not decrease. Choice D is incorrect because the density increases as the volume decreases, not decreases.

2. How do you determine the velocity of a wave?

• A. Multiply the frequency by the wavelength.
• B. Add the frequency and the wavelength.
• C. Subtract the wavelength from the frequency.
• D. Divide the wavelength by the frequency.

Correct answer: A

Rationale: The velocity of a wave can be determined by multiplying the frequency of the wave by the wavelength. This relationship is given by the formula: velocity = frequency × wavelength. By multiplying the frequency by the wavelength, you can calculate the speed at which the wave is traveling. This formula is derived from the basic wave equation v = f × λ, where v represents velocity, f is frequency, and λ is wavelength. Therefore, to find the velocity of a wave, one must multiply its frequency by its wavelength. Choices B, C, and D are incorrect. Adding, subtracting, or dividing the frequency and wavelength does not yield the correct calculation for wave velocity. The correct formula for determining wave velocity is to multiply the frequency by the wavelength.

3. Which of these substances is most compressible?

• A. Gold
• B. Water
• C. Mercury
• D. Methane

Correct answer: D

Rationale: Methane, a gas at room temperature and pressure, is the most compressible substance among the options provided. Gases are generally more compressible compared to liquids and solids because their particles have more space between them, allowing for greater compression when pressure is applied. Gold, water, and mercury, being solid and liquid substances, respectively, have particles arranged closely together, making them less compressible. Therefore, the correct answer is Methane.

4. A pitcher throws a 45-g baseball at a velocity of 42 meters per second. What is the ball’s momentum?

• A. 0.189 kg⋅m/s
• B. 1.89 kg⋅m/s
• C. 1.07 kg⋅m/s
• D. 0.93 kg⋅m/s

Correct answer: B

Rationale: Momentum is calculated by multiplying mass (in kg) by velocity (in m/s). The mass of the baseball is 0.045 kg (45 grams converted to kg), and the velocity is 42 m/s. Momentum = 0.045 kg × 42 m/s = 1.89 kg⋅m/s. Therefore, the correct answer is 1.89 kg⋅m/s. Choice A is incorrect as it incorrectly converts the mass from grams to kg. Choice C and D are incorrect due to calculation errors.

5. The Reynolds number (Re) is a dimensionless quantity used to characterize:

• A. Fluid density
• B. Flow regime (laminar vs. turbulent)
• C. Surface tension effects
• D. Buoyancy force magnitude

Correct answer: B

Rationale: The Reynolds number is a dimensionless quantity used to characterize the flow regime, specifically whether it is laminar (smooth) or turbulent (chaotic). It depends on the velocity of the fluid, its characteristic length (such as pipe diameter), and its viscosity. A low Reynolds number indicates laminar flow, while a high Reynolds number suggests turbulence. Choices A, C, and D are incorrect because the Reynolds number is not related to fluid density, surface tension effects, or buoyancy force magnitude.

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