when a fluid encounters a bluff body eg a car the flow can separate behind the object creating a region of low pressure this phenomenon is known as

HESI A2

HESI A2 Physics Practice Test

1. When a fluid encounters a bluff body (e.g., a car), the flow can separate behind the object, creating a region of low pressure. This phenomenon is known as:

A. Cavitation
B. Boundary layer separation
C. Bernoulli effect per se
D. Drag crisis

Correct answer: B

Rationale: The correct answer is B: Boundary layer separation. Boundary layer separation occurs when the flow of fluid detaches from the surface of a bluff body, leading to a low-pressure region behind the object. This separation creates a wake region with reduced pressure. Choice A, Cavitation, refers to the formation of vapor bubbles in a fluid and is not relevant in this context. Choice C, Bernoulli effect per se, does not specifically describe the phenomenon of flow separation behind a bluff body. Choice D, Drag crisis, is not the term used to describe the creation of a low-pressure region due to flow separation.

2. What is the pH of acids?

A. 7.5
B. < 7
C. > 7
D. 7

Correct answer: B

Rationale: The correct answer is B: < 7. Acids have a pH lower than 7, indicating higher acidity. A pH below 7 signifies an acidic solution, with lower values indicating stronger acids. Choice A (7.5) is incorrect as it is greater than 7, which is alkaline. Choice C (> 7) is incorrect as values greater than 7 represent alkaline/basic solutions. Choice D (7) is incorrect because a pH of 7 is neutral, not acidic.

3. Which claim from the passage best describes the benefits of nanotechnology?

A. Scientists can develop novel technologies and products.
B. Nanotechnology is defined as the understanding and control of matter at dimensions of roughly 1 to 100 nanometers.
C. The different colors can be used in simple medical tests to indicate infection or disease.
D. Unique properties of materials emerge.

Correct answer: D

Rationale: The correct answer is D because the passage specifically states that at the nanoscale, unique properties of materials emerge, which is a key benefit of nanotechnology. Choice A talks about what scientists can do but does not directly describe the benefits mentioned in the passage. Choice B is the definition of nanotechnology and not a specific benefit. Choice C mentions the use of different colors in medical tests, which is a specific application rather than a general benefit of nanotechnology.

4. What does 'Impending' mean?

A. Likely to never occur
B. Likely to occur soon
C. Certain to never occur
D. Unlikely to occur

Correct answer: B

Rationale: The correct answer is B: 'Likely to occur soon.' 'Impending' is used to describe something that is about to happen or is looming in the near future. Choices A, C, and D are incorrect because 'Impending' does not indicate that something is unlikely, certain to never occur, or likely to never occur.

5. Choose the meaning of the word rationale in the following sentence: "Step-by-step, the doctor explained the rationale for the treatment."

A. Reasoning
B. Prescription
C. Procedure
D. Necessity

Correct answer: A

Rationale: Corrected Question: In this context, the word 'rationale' refers to the underlying reasoning or justification for the treatment being explained step-by-step by the doctor. It pertains to the logical basis or thought process behind the chosen course of action. 'Prescription' (Choice B), 'Procedure' (Choice C), and 'Necessity' (Choice D) do not accurately capture the meaning of 'rationale' in the sentence provided.