---
title: "A horizontal tube with two vertical T-branches (A and B) is partially submerged in a liquid, with the open ends of the branches exposed to the air. However, the section of the tube above point B is hidden from view and may either be wider or narrower than the section above A.  Air is blown through the horizontal tube, causing the liquid levels in the vertical branches to rise as shown. Based on the observed water levels, which of the following best describes the characteristics of the hidden section of the tube above B?"
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url: "https://nerd-notes.com/ubq/79303/"
date_modified: "2025-03-04T08:10:20+00:00"
---

# A horizontal tube with two vertical T-branches (A and B) is partially submerged in a liquid, with the open ends of the branches exposed to the air. However, the section of the tube above point B is hidden from view and may either be wider or narrower than the section above A.  Air is blown through the horizontal tube, causing the liquid levels in the vertical branches to rise as shown. Based on the observed water levels, which of the following best describes the characteristics of the hidden section of the tube above B?

A horizontal tube with two vertical T-branches (A and B) is partially submerged in a liquid, with the open ends of the branches exposed to the air. **However**, the section of the tube above point B is hidden from view and may either be wider or narrower than the section above A.

Air is blown through the horizontal tube, causing the liquid levels in the vertical branches to rise as shown. Based on the observed water levels, which of the following best describes the characteristics of the hidden section of the tube above B?

![Diagram](https://nerd-notes.com/wp-content/uploads/2025/03/airoversubmergedtubes.jpg)

- **A.** The tube is wider, and the air speed is greater above section B.
- **B.** The diagram is incorrect—points A and B must have the same liquid height.
- **C.** The tube is narrower, and the air speed is greater above section B.
- **D.** The tube is narrower, and the air speed is lower above section B.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/79303/*