Nursing Elites

1. A concave mirror with a focal length of 2 cm forms a real image of an object at an image distance of 6 cm. What is the object's distance from the mirror?

• A. 3 cm
• B. 6 cm
• C. 12 cm
• D. 30 cm

Correct answer: B

Rationale: The mirror formula, 1/f = 1/do + 1/di, can be used to solve for the object distance. Given that the focal length (f) is 2 cm and the image distance (di) is 6 cm, we can substitute these values into the formula to find the object distance. Plugging in f = 2 cm and di = 6 cm into the formula gives us 1/2 = 1/do + 1/6. Solving for do, we get do = 6 cm. Therefore, the object's distance from the mirror is 6 cm. Choice A (3 cm), Choice C (12 cm), and Choice D (30 cm) are incorrect distances as the correct object distance is determined to be 6 cm.

2. Which object below has the same density?

• A. A block with a mass of 6.5 grams and a volume of 16.25 cm3
• B. A block with a mass of 80 grams and a volume of 32 cm3
• C. A block with a mass of 48 grams and a volume of 22 cm3
• D. A block with a mass of 100 grams and a volume of 250 cm3

Correct answer: A

Rationale: Density is calculated by dividing the mass of an object by its volume. The density of object A is 6.5 g / 16.25 cm3 = 0.4 g/cm3. The density of object B is 80 g / 32 cm3 = 2.5 g/cm3. The density of object C is 48 g / 22 cm3 = 2.18 g/cm3. The density of object D is 100 g / 250 cm3 = 0.4 g/cm3. Objects A and D have the same density of 0.4 g/cm3. Therefore, the correct answer is A as it has the same density as object D, making them the only objects with a density of 0.4 g/cm3.

3. According to Bernoulli's principle, when the flow velocity (v) of an incompressible fluid increases in a constricted pipe, the pressure (P) will:

• A. Depend on the specific fluid type
• B. Decrease
• C. Remain constant
• D. Increase

Correct answer: B

Rationale: Bernoulli's principle states that in a constricted pipe with increasing flow velocity of an incompressible fluid, the pressure decreases. This is due to the conservation of energy, where the total energy of the fluid (sum of kinetic energy, potential energy, and pressure energy) remains constant along the flow path. As the fluid velocity increases, its kinetic energy increases at the expense of pressure energy, causing a decrease in pressure. Therefore, the correct answer is B. Choices A, C, and D are incorrect. The pressure changes in the system are primarily driven by the fluid velocity and the conservation of energy principle, not by the specific fluid type, which is a constant. The pressure is not constant but decreases with increasing flow velocity due to the energy transformation occurring in the system. Lastly, the pressure does not increase; it decreases as the fluid velocity rises.

4. Which substance would be most affected by a change in temperature?

• A. Liquid nitrogen
• B. Salt crystals
• C. Hydrogen gas
• D. Iron filings

Correct answer: C

Rationale: Hydrogen gas would be most affected by a change in temperature because gases have a greater expansion or contraction in volume with changes in temperature compared to liquids or solids. When the temperature of hydrogen gas increases, its molecules gain kinetic energy and move faster, causing the gas to expand and its volume to increase. Conversely, when the temperature decreases, the gas molecules lose kinetic energy and move slower, leading to a decrease in volume. This property makes hydrogen gas highly sensitive to temperature changes compared to liquid nitrogen, salt crystals, or iron filings. Liquid nitrogen, salt crystals, and iron filings are less affected by temperature changes because their particles are closer together and have lower kinetic energy, resulting in minimal volume changes with temperature fluctuations.

5. In hydraulic systems, Pascal's principle states that a pressure change applied to a confined incompressible fluid is:

• A. Amplified but loses energy
• B. Transmitted undiminished throughout the fluid
• C. Limited by the container size
• D. Dependent on the fluid type

Correct answer: B

Rationale: Pascal's principle states that when a pressure change is applied to a confined incompressible fluid, the resulting pressure change is transmitted undiminished throughout the fluid. This means that the pressure change will be the same at every point in the fluid, regardless of the container size or the type of fluid used. Therefore, choice B is the correct answer. Choices A, C, and D are incorrect because Pascal's principle specifically emphasizes the transmission of pressure without amplification, limitation by container size, or dependence on the fluid type.

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