Nursing Elites

1. When a small object floats on the surface of a liquid, the surface tension creates a:

• A. Buoyant force acting upwards
• B. Pressure difference causing sinking
• C. Drag force opposing motion
• D. Restoring force towards equilibrium

Correct answer: D

Rationale: Surface tension creates a restoring force that holds the object on the surface. The liquid's surface behaves like a stretched membrane, and when disturbed, it tends to return the object to its original position, creating a restoring force. The other choices are incorrect: A buoyant force acts on objects submerged in a fluid, not floating on the surface; pressure differences usually affect sinking objects, not floating ones; drag force is a resistance force that opposes motion, not related to surface tension.

2. Archimedes' principle explains the ability to control buoyancy, allowing:

• A. Objects to sink regardless of density differences.
• B. Airplanes to generate lift for flight.
• C. Submarines to adjust their buoyancy for submergence and resurfacing.
• D. Helium balloons to overcome gravity and float.

Correct answer: C

Rationale: Archimedes' principle states that the upward buoyant force acting on an object submerged in a fluid is equal to the weight of the fluid displaced by the object. Submarines control their buoyancy by adjusting the volume of water they displace, which allows them to submerge and resurface. Choice C is correct because it directly relates to the principle of buoyancy and how submarines utilize it. Choices A, B, and D are incorrect because they do not accurately reflect the application of Archimedes' principle in controlling buoyancy for submergence and resurfacing.

3. The drag force (F_d) experienced by an object moving through a fluid depends on:

• A. Object's shape and size only
• B. Fluid properties and object velocity
• C. Depth of submersion only
• D. Buoyant force acting on the object

Correct answer: B

Rationale: The drag force experienced by an object moving through a fluid depends on multiple factors, including the object's shape, size, velocity, and the fluid's properties such as viscosity and density. Choices A, C, and D are incorrect because drag force is not solely determined by the object's shape and size, depth of submersion, or buoyant force acting on the object. The primary factors affecting drag force are the fluid properties and the object's velocity. Therefore, the correct answer is B.

4. 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.

5. In the mechanical power equation P = E / t, power is measured in ___________.

• A. ohms
• B. Joules
• C. volts
• D. watts

Correct answer: D

Rationale: In the mechanical power equation P = E / t, power is measured in watts. Watts are the standard unit of power in the International System of Units (SI), named after the Scottish engineer James Watt. Watts are defined as joules per second, reflecting the rate at which energy is transferred or converted. Ohms (choice A) are the unit of electrical resistance, Joules (choice B) are the unit of energy, and volts (choice C) are the unit of electric potential difference. Therefore, the correct answer is watts as it directly relates to power in the given equation.

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