HESI A2 Physics Quizlet

Correct Answer: B

Rationale: The correct answer is B: ṁ = ρvA. This equation is derived from the continuity equation, which states that mass flow rate ṁ remains constant in steady flow. Mass flow rate ṁ is the product of fluid density ρ, cross-sectional area A, and average velocity v. This relationship is crucial for understanding the behavior of fluids in pipes. Choice A is incorrect because the mass flow rate can be determined using the given equation without any additional information. Choice C is incorrect because Bernoulli's principle is not directly related to the calculation of mass flow rate. Choice D is incorrect because the equation of state for the specific fluid is not required to determine the mass flow rate using the continuity equation.

Correct Answer: D

Rationale: Step 1: The mechanical power equation is P = E / t, where P is power, E is energy, and t is time. Step 2: Power is the rate at which work is done or energy is transferred. Step 3: The SI unit of power is the watt (W), representing one joule per second. Step 4: Therefore, the correct answer is D: watts. Summary: - A: Ohms is the unit of electrical resistance, not power. - B: Joules is the unit of energy, not power. - C: Volts is the unit of electrical potential difference, not power.

Correct Answer: C

Rationale: The correct answer is C: Boundary layer effect. The boundary layer is the thin layer of fluid that adheres to a solid surface in fluid flow. This occurs due to viscosity, which causes the fluid particles to stick to the surface. This layer affects the overall flow behavior and drag force on the object. Buoyancy (A) is the upward force exerted on an object submerged in a fluid. Bernoulli's principle (B) relates to the conservation of energy in fluid flow. Surface tension minimization (D) pertains to minimizing the surface area of a liquid to reduce its surface tension, not relevant to the adherence of fluid to a solid surface in flow.

Correct Answer: B

Rationale: Rationale: Viscosity is the resistance of a fluid to flow. It determines how easily a fluid can flow and is crucial in various applications like fluid dynamics. In contrast, inertia (choice A) is related to the mass of an object, not a property of a fluid. Compressibility (choice C) refers to the change in volume of a fluid under pressure, not its resistance to flow. Buoyancy generation (choice D) is related to the upward force exerted on an object immersed in a fluid, not a property of the fluid itself. Therefore, the correct answer is B as it directly relates to the definition and significance of viscosity.

Correct Answer: A

Rationale: To calculate density, divide the mass by the volume. In this case, 24 g / 6 cm3 = 4 g/cm3. This is the correct answer (A) because density is expressed in units of mass per volume. Choice B is incorrect as it has the inverse units. Choices C and D are incorrect as they do not match the calculated value based on the given mass and volume.