Nursing Elites

1. Which of the following is NOT a mode of heat transfer between a system and its surroundings?

• A. Conduction
• B. Convection
• C. Radiation
• D. Isothermalization

Correct answer: A

Rationale: Isothermalization is not a mode of heat transfer. The three main modes of heat transfer are conduction (through direct contact), convection (through fluid motion), and radiation (through electromagnetic waves). In this question, choice A, conduction, is not a mode of heat transfer between a system and its surroundings. Conduction refers to heat transfer through direct contact between particles, without the movement of the particles themselves. Therefore, A is the correct answer. Choices B, C, and D are incorrect as they represent valid modes of heat transfer.

2. Power (P) represents the rate of work done. Which formula accurately depicts power?

• A. P = W / F
• B. P = d / t
• C. P = W x t
• D. P = F / t

Correct answer: D

Rationale: Power (P) is defined as the rate of work done over time. The correct formula for power is P = W/t, where W is the work done, and t is the time taken. Therefore, option D, P = F / t, correctly represents power as work divided by time. Option A, P = W / F, is incorrect as it represents work divided by force, not power. Option B, P = d / t, is incorrect as it represents distance divided by time, not power. Option C, P = W x t, is incorrect as it represents work multiplied by time, not power. It's important to understand the distinction between work, power, force, time, and other related concepts to solve physics problems accurately.

3. A 5-cm candle is placed 20 cm away from a concave mirror with a focal length of 10 cm. What is the image distance of the candle?

• A. 20 cm
• B. 40 cm
• C. 60 cm
• D. 75 cm

Correct answer: C

Rationale: To find the image distance of the candle, we use the mirror formula: 1/f = 1/do + 1/di, where f is the focal length, do is the object distance, and di is the image distance. In this case, the focal length f = 10 cm and the object distance do = 20 cm. Substituting these values into the formula gives us 1/10 = 1/20 + 1/di. Solving for di, we get di = 60 cm. Therefore, the image distance of the candle is 60 cm. Choice A (20 cm) is incorrect because it represents the object distance, not the image distance. Choice B (40 cm) is incorrect as it does not consider the mirror formula calculation. Choice D (75 cm) is incorrect as it does not match the correct calculation based on the mirror formula.

4. A 10-kg object moving at 5 m/s has an impulse acted on it causing the velocity to change to 15 m/s. What was the impulse that was applied to the object?

• A. 10 kg⋅m/s
• B. 15 kg⋅m/s
• C. 20 kg⋅m/s
• D. 100 kg⋅m/s

Correct answer: D

Rationale: Impulse is the change in momentum of an object. The initial momentum is calculated as 10 kg × 5 m/s = 50 kg⋅m/s, and the final momentum is 10 kg × 15 m/s = 150 kg⋅m/s. The change in momentum (impulse) is 150 kg⋅m/s - 50 kg⋅m/s = 100 kg⋅m/s. Therefore, the impulse applied to the object is 100 kg⋅m/s. Choices A, B, and C are incorrect because they do not reflect the correct calculation of the impulse based on the change in momentum of the object.

5. 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.

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