Nursing Elites

1. The speed of sound in dry air at 20°C is 343 m/s. If the wavelength of a sound wave is 5 m, what is its frequency?

• A. 171.5 Hz
• B. 79 Hz
• C. 68.6 Hz
• D. 63.6 Hz

Correct answer: C

Rationale: The speed of sound (v) can be calculated using the formula: v = f × λ, where f is the frequency and λ is the wavelength. Given that the speed of sound is 343 m/s and the wavelength is 5 m, we can rearrange the formula to solve for frequency: f = v / λ = 343 / 5 = 68.6 Hz. Therefore, the correct frequency is 68.6 Hz. Choices A, B, and D are incorrect as they do not result from the correct calculation based on the given values.

2. Which property of a substance does not change with a change in temperature?

• A. Mass
• B. Volume
• C. Phase
• D. Solubility

Correct answer: A

Rationale: Mass is an intrinsic property of a substance that remains constant regardless of temperature changes. It is a measure of the amount of matter in an object, and this quantity does not vary with temperature or the environment in which the substance is located. The conservation of mass in chemistry dictates that mass is neither created nor destroyed, making it independent of temperature variations.\nVolume, on the other hand, changes with temperature due to thermal expansion or contraction. Phase can change with temperature, leading to transitions between solid, liquid, and gas states. Solubility is affected by temperature changes as it influences the ability of a substance to dissolve in a solvent.

3. Fluids can be categorized based on their shear stress-strain rate relationship. An ideal fluid exhibits:

• A. Zero shear stress at any strain rate
• B. Linear relationship between shear stress and strain rate (Newtonian)
• C. Non-linear relationship between shear stress and strain rate (Non-Newtonian)
• D. High dependence of viscosity on temperature

Correct answer: A

Rationale: An ideal fluid, often referred to as an inviscid fluid, is a theoretical concept used in fluid mechanics to simplify calculations. It is characterized by having zero shear stress at any strain rate. In reality, such fluids do not exist, but they serve as a useful starting point for understanding fluid behavior in idealized situations. Choice B is incorrect because a linear relationship between shear stress and strain rate defines a Newtonian fluid, not an ideal fluid. Choice C is incorrect because a non-linear relationship between shear stress and strain rate characterizes Non-Newtonian fluids, not ideal fluids. Choice D is incorrect because the high dependence of viscosity on temperature is a characteristic seen in real fluids and does not define an ideal fluid.

4. If a force of 12 kg stretches a spring by 3 cm, how far will the spring stretch when a force of 30 kg is applied?

• A. 6 cm
• B. 7.5 cm
• C. 9 cm
• D. 10.5 cm

Correct answer: B

Rationale: The extension of a spring is directly proportional to the force applied. In this case, the force increases from 12 kg to 30 kg, which is a 2.5 times increase. Therefore, the extension of the spring will also increase by 2.5 times. Given that the spring stretches 3 cm with a force of 12 kg, multiplying 3 cm by 2.5 gives us the extension of the spring when a force of 30 kg is applied, which equals 7.5 cm. Therefore, the correct answer is 7.5 cm. Choice A, 6 cm, is incorrect because it does not account for the proportional increase in force. Choice C, 9 cm, and Choice D, 10.5 cm, are incorrect as they overestimate the extension of the spring by not considering the direct proportionality between force and extension.

5. A plucked guitar string makes 80 vibrations in one second. What is the period?

• A. 0.0125 s
• B. 0.025 s
• C. 0.125 s
• D. 0.25 s

Correct answer: B

Rationale: The period is the time taken for one complete vibration of the guitar string. To find the period, you need to take the reciprocal of the frequency. Since the string makes 80 vibrations in one second, the period is 1/80 = 0.0125 seconds (or 0.025 s). Choice A is incorrect because it is the reciprocal of 80. Choice C is incorrect as it is 10 times the reciprocal of 80. Choice D is incorrect as it is 100 times the reciprocal of 80.

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