HESI A2
HESI Exams Quizlet Physics
1. 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.
2. A closed system undergoes a cyclic process, returning to its initial state. What can be said about the net work done (Wnet) by the system over the entire cycle?
- A. Wnet is always positive.
- B. Wnet is always negative.
- C. Wnet can be positive, negative, or zero.
- D. Wnet is equal to the total heat transferred into the system (dQ ≠ 0 for a cycle).
Correct answer: C
Rationale: For a closed system undergoing a cyclic process and returning to its initial state, the net work done (Wnet) over the entire cycle can be positive, negative, or zero. This is because the work done is determined by the area enclosed by the cycle on a P-V diagram, and this area can be above, below, or intersecting the zero work axis, leading to positive, negative, or zero net work done. Choice A is incorrect because Wnet is not always positive; it depends on the specific path taken on the P-V diagram. Choice B is incorrect as Wnet is not always negative; it varies based on the enclosed area. Choice D is incorrect because Wnet is not necessarily equal to the total heat transferred into the system; it depends on the specifics of the cycle and is not a direct relationship.
3. 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.
4. When calculating an object’s acceleration, what must you do?
- A. Divide the change in time by the velocity.
- B. Multiply the velocity by the time.
- C. Find the difference between the time and velocity.
- D. Divide the change in velocity by the change in time.
Correct answer: D
Rationale: When calculating an object's acceleration, you must divide the change in velocity by the change in time. Acceleration is defined as the rate of change of velocity with respect to time. By determining the ratio of the change in velocity to the change in time, you can ascertain how quickly the velocity of an object is changing, thereby finding its acceleration. Choice A is incorrect because acceleration is not calculated by dividing time by velocity. Choice B is incorrect as it describes multiplying velocity by time, which does not yield acceleration. Choice C is incorrect as finding the difference between time and velocity is not a method to calculate acceleration.
5. An incandescent lamp consumes 60 Joules of energy per second. What is the power rating of this lamp?
- A. 1 Watt (W)
- B. 60 Watts (W)
- C. 1/60 Joules
- D. Impossible to determine without knowing the voltage
Correct answer: B
Rationale: Power is defined as energy consumed per unit time. If the lamp consumes 60 Joules of energy per second, the power rating is 60 Watts. Therefore, choice B is correct. Choice A ('1 Watt') is incorrect because the lamp consumes 60 Joules per second, not 1 Joule per second. Choice C ('1/60 Joules') is incorrect as it does not represent the power rating. Choice D ('Impossible to determine without knowing the voltage') is incorrect because power can be calculated using energy consumption per unit time without needing to know the voltage.
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