Nursing Elites

1. In Einstein’s mass-energy equation, what is represented by c?

• A. Distance in centimeters
• B. The speed of light
• C. Degrees Celsius
• D. Centrifugal force

Correct answer: B

Rationale: In Einstein's mass-energy equation, E=mc^2, the symbol 'c' represents the speed of light in a vacuum, which is approximately equal to 3.00 x 10^8 meters per second. This equation demonstrates the equivalence of energy (E) and mass (m) and is a fundamental concept in the theory of relativity. Choice A is incorrect as 'c' does not represent distance in centimeters. Choice C is incorrect as 'c' does not represent degrees Celsius. Choice D is incorrect as 'c' does not represent centrifugal force.

2. Amanda uses 100 N of force to push a lawnmower around her lawn. If she mows 20 rows measuring 30 meters each, how much work does she do?

• A. 3,000 N⋅m
• B. 6,000 N⋅m
• C. 60,000 N⋅m
• D. The answer cannot be determined from the information given.

Correct answer: C

Rationale: The work done by Amanda pushing the lawnmower is calculated by multiplying the force applied (100 N) by the distance over which the force is applied (the total distance mowed). Since Amanda mows 20 rows, each measuring 30 meters, the total distance mowed is 20 rows x 30 meters/row = 600 meters. Therefore, the work done is 100 N x 600 m = 60,000 N⋅m. Option A and B are incorrect as they do not account for the total distance mowed. Option D is incorrect as the work done can be accurately calculated based on the information provided.

3. The efficiency (η) of a heat engine is defined as the ratio of the net work done (Wnet) by the engine to the heat input (Qh) from the hot reservoir. The relationship is expressed as:

• A. η = Wnet / Qh
• B. η = Qh / Wnet
• C. η = Wnet x Qh
• D. η = (Wnet + Qh) / 2

Correct answer: A

Rationale: The correct formula for efficiency (η) of a heat engine is η = Wnet / Qh. Efficiency is defined as the ratio of the net work done by the engine (Wnet) to the heat input from the hot reservoir (Qh). This formula shows how effectively the engine converts heat into useful work, making choice A the correct answer. Choices B, C, and D present incorrect relationships between efficiency, net work done, and heat input, leading to their incorrectness.

4. Why are boats more buoyant in salt water than in fresh water?

• A. Salt decreases the mass of the boats.
• B. Salt increases the volume of the water.
• C. Salt affects the density of the boats.
• D. Salt increases the density of the water.

Correct answer: D

Rationale: Salt increases the density of water, making saltwater more buoyant than freshwater. The higher density of saltwater provides more lift to a boat, enabling it to float more easily compared to in freshwater. Choice A is incorrect because salt does not affect the mass of the boats. Choice B is incorrect as salt does not increase the volume of water. Choice C is incorrect since salt affects the density of water, not the boats themselves. Therefore, the correct answer is that salt increases the density of the water, resulting in boats being more buoyant in salt water than in fresh water.

5. What characterizes laminar flow?

• A. Smooth, parallel layers of fluid particles
• B. Erratic and turbulent motion of fluid particles
• C. High viscosity hindering flow
• D. Incompressibility of the fluid

Correct answer: A

Rationale: Laminar flow is characterized by the smooth, parallel movement of fluid particles along layers in a predictable manner. This flow regime occurs at low velocities and is in contrast to turbulent flow, where fluid particles exhibit erratic and chaotic motion. The viscosity of the fluid does not hinder laminar flow; instead, it influences the resistance to flow. Incompressibility is a property of fluids but does not specifically define laminar flow. Therefore, the correct answer is A as it accurately describes the behavior of fluid particles in laminar flow, making B, C, and D incorrect.

Similar Questions