Nursing Elites

1. As a car is traveling on the highway, its speed drops from 60 mph to 30 mph. What happens to its kinetic energy?

• A. Its energy is halved.
• B. Its energy is doubled.
• C. Its energy is quadrupled.
• D. Its energy is divided by four.

Correct answer: A

Rationale: The correct answer is A. Kinetic energy is proportional to the square of the velocity. When the speed drops from 60 mph to 30 mph, the kinetic energy is halved. Choice B is incorrect because halving the speed results in halving the kinetic energy, not doubling it. Choice C is incorrect because quadrupling the kinetic energy would require increasing the speed fourfold, not halving it. Choice D is incorrect because dividing the energy by four would imply a different relationship between speed and kinetic energy, which is not the case.

2. In fluid dynamics, the continuity equation, a fundamental principle, expresses the conservation of:

• A. Momentum
• B. Mass
• C. Energy
• D. Angular momentum

Correct answer: B

Rationale: The continuity equation in fluid dynamics is a statement of the conservation of mass, making choice B the correct answer. It states that the mass entering a system must equal the mass leaving the system, assuming no mass is created or destroyed within the system. Conservation of momentum (choice A) is related to Newton's laws of motion and is not directly expressed by the continuity equation. Conservation of energy (choice C) involves different principles like the first law of thermodynamics and is not the focus of the continuity equation. Angular momentum (choice D) is also a different concept related to rotational motion and not described by the continuity equation.

3. A Carnot cycle is a theoretical ideal heat engine operating between two heat reservoirs at different temperatures. Which of the following statements is NOT true about a Carnot cycle?

• A. The efficiency of a Carnot cycle is solely dependent on the absolute temperatures of the hot and cold reservoirs.
• B. It is a reversible cycle, meaning the process can be run in both directions with the same efficiency.
• C. It operates isothermally at the hot and cold reservoir temperatures.
• D. It is the most efficient heat engine operating between the same two reservoir temperatures.

Correct answer: C

Rationale: The statement that is NOT true is C. Although part of the Carnot cycle operates isothermally, not the entire cycle operates isothermally. The Carnot cycle consists of both isothermal and adiabatic processes. Choice A is incorrect because the efficiency of a Carnot cycle is indeed solely dependent on the absolute temperatures of the hot and cold reservoirs. Choice B is correct as a Carnot cycle is reversible, allowing the process to be run in both directions with the same efficiency. Choice D is also true as the Carnot cycle is the most efficient heat engine operating between the same two reservoir temperatures. Therefore, the correct answer is C.

4. When two identical charged spheres, both positively charged, are brought close together, the electrostatic force between them will be:

• A. Slightly attractive
• B. Zero
• C. Strongly attractive
• D. Strongly repulsive

Correct answer: D

Rationale: When two positively charged spheres are brought close together, they will experience a repulsive force due to their like charges. The electrostatic force causes the spheres to repel each other, making the correct answer D: Strongly repulsive. The force is not dependent on the material of the spheres, and the force is definitely not zero, as like charges repel. Choice A is incorrect as like charges do not attract each other. Choice C is incorrect as like charges repel, not attract.

5. What is the net force acting on the car?

• A. 450 N
• B. 700 N
• C. 1,500 N
• D. 6,300 N

Correct answer: C

Rationale: To determine the net force acting on an object, we need to consider the sum of the forces acting in the same direction and subtract the forces acting in the opposite direction. In this scenario, there is a force of 4,200 N to the right and a force of 2,700 N to the left. By subtracting the leftward force from the rightward force (4,200 N - 2,700 N), we find that the net force acting on the car is 1,500 N to the right. Therefore, choice C, 1,500 N, is the correct answer. Choice A, 450 N, is too small as it does not account for the total forces involved. Choice B, 700 N, is also incorrect as it is not the result of the correct mathematical operation on the given forces. Choice D, 6,300 N, is too large and does not align with the calculation based on the forces provided.

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