HESI A2 Physics Practice Test

Questions 42

HESI A2

HESI A2 Test Bank

HESI A2 Physics Practice Test Questions

Question 1 of 5

Enthalpy (H) is a thermodynamic property defined as the sum of a system's internal energy (U) and the product of its pressure (P) and volume (V). The relationship between these is:

Correct Answer: A

Rationale: The correct answer is A: H = U + PV. Enthalpy (H) is defined as H = U + PV, where U is internal energy, P is pressure, and V is volume. This equation comes from the first law of thermodynamics, which states that the change in internal energy of a system is equal to the heat added to the system minus the work done by the system. In this case, the work done by the system is PΔV, which represents the product of pressure and volume. Therefore, the correct relationship between enthalpy, internal energy, pressure, and volume is H = U + PV. Choices B, C, and D are incorrect because they do not accurately represent the definition of enthalpy. Choice B (H = U - PV) is incorrect because it subtracts the product of pressure and volume from internal energy, which is not the correct relationship. Choice C (H = U / PV) is incorrect because it divides internal

Question 2 of 5

When analyzing a power plant, which of the following is NOT considered a part of the system?

Correct Answer: D

Rationale: The surrounding air is NOT considered a part of the system when analyzing a power plant as it acts as the environment outside the system boundary. The system typically includes components directly involved in the energy conversion process, such as the fuel, working fluid, and turbine. The surrounding air, while it may have an impact on the plant's operations, is not a component within the system boundary and does not play a direct role in the energy conversion process. Choices A, B, and C are all integral parts of the power plant system as they are directly involved in the conversion of energy from the fuel to electricity.

Question 3 of 5

Which conclusion can be drawn from Ohm's law?

Correct Answer: B

Rationale: The correct answer is B: The ratio of the potential difference between the ends of a conductor to current is a constant, R. This is in accordance with Ohm's law, which states that V (voltage) = I (current) x R (resistance). Ohm's law establishes a direct proportionality between voltage and current when resistance is constant. The constant R represents the resistance of the conductor. Option A is incorrect because voltage and current are directly proportional when resistance is constant, not inversely proportional. Option C is incorrect as voltage is not the amount of charge passing through a point per second, but rather the potential difference. Option D is incorrect as power is calculated using the formula P = VI, not I x V.

Question 4 of 5

Fluids can be categorized based on their shear stress-strain rate relationship. An ideal fluid exhibits:

Correct Answer: A

Rationale: Rationale: An ideal fluid exhibits zero shear stress at any strain rate. This is because an ideal fluid is assumed to have no resistance to flow, resulting in no shear stress being generated regardless of the strain rate. This is a fundamental characteristic of an ideal fluid and distinguishes it from real fluids that exhibit varying levels of shear stress. Summary: - Choice A is correct as an ideal fluid exhibits zero shear stress at any strain rate. - Choice B is incorrect as it describes a Newtonian fluid which has a linear relationship between shear stress and strain rate. - Choice C is incorrect as it describes a Non-Newtonian fluid with a non-linear relationship between shear stress and strain rate. - Choice D is incorrect as it describes the temperature dependence of viscosity, which is not a defining characteristic of an ideal fluid.

Question 5 of 5

Household alternating current typically has a frequency of 60 Hz. Which statement is true?

Correct Answer: D

Rationale: The correct answer is D. Electrons complete a cycle 60 times per second in a 60 Hz household alternating current. This is because the frequency of AC refers to the number of complete cycles per second. Electrons moving back and forth create the alternating current flow. A: Incorrect. The power rating of a bulb (in watts) is determined by the voltage and current, not the frequency. B: Incorrect. The current in household circuits is typically much lower than 60 amperes for safety reasons. C: Incorrect. Voltage drop is dependent on the resistance in the wire and the current flowing, not the frequency of the current.

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