Nursing Elites

1. 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.

2. A 2,000-kg car travels at 15 m/s. For a 1,500-kg car traveling at 15 m/s to generate the same momentum, what would need to happen?

• A. It would need to accelerate to 20 m/s.
• B. It would need to add 500 kg in mass.
• C. Both A and B
• D. Either A or B

Correct answer: A

Rationale: Momentum is calculated as the product of mass and velocity. Since momentum is conserved in the absence of external forces, for the 1,500-kg car to generate the same momentum as the 2,000-kg car at 15 m/s, it would need to increase its velocity to compensate for the difference in mass. Accelerating to 20 m/s would achieve this without needing to change the mass of the car. Choice B is incorrect because adding mass is not necessary to match momentum in this scenario.

3. 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.

4. An object with a mass of 45 kg has momentum equal to 180 kg⋅m/s. What is the object’s velocity?

• A. 4 m/s
• B. 8.1 km/s
• C. 17.4 km/h
• D. 135 m/s

Correct answer: A

Rationale: The momentum of an object is calculated by multiplying its mass and velocity. Mathematically, momentum = mass x velocity. Given that the mass is 45 kg and the momentum is 180 kg⋅m/s, we can rearrange the formula to solve for velocity: velocity = momentum / mass. Plugging in the values, velocity = 180 kg⋅m/s / 45 kg = 4 m/s. Therefore, the object's velocity is 4 m/s. Choices B, C, and D are incorrect because they do not align with the correct calculation based on the given mass and momentum values.

5. A car, starting from rest, accelerates at 10 m/s² for 5 seconds. What is the velocity of the car after 5 seconds?

• A. 2 m/s
• B. 5 m/s
• C. 50 m/s
• D. The answer cannot be determined from the information given.

Correct answer: C

Rationale: The velocity of an object can be calculated using the formula: final velocity = initial velocity + (acceleration × time). In this case, the car starts from rest, so the initial velocity is 0 m/s. Given that the acceleration is 10 m/s² and the time is 5 seconds, we can plug these values into the formula to find the final velocity: final velocity = 0 m/s + (10 m/s² × 5 s) = 0 m/s + 50 m/s = 50 m/s. Therefore, the velocity of the car after 5 seconds is 50 m/s. Choice A (2 m/s) and Choice B (5 m/s) are incorrect because they do not consider the acceleration the car undergoes over the 5 seconds, resulting in a final velocity greater than both. Choice D (The answer cannot be determined from the information given) is incorrect as the final velocity can be determined using the provided data and the kinematic equation.

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