What is U-tube manometer used for?

Options

A. To measure force applied by liquids direction?
B. To measure density of liquids
C. To measure liquid pressure
D. To measure liquid volume

Answer

**Step-by-Step Solution:**

1. **Understanding the U-tube Manometer**: A U-tube manometer is a device that consists of a U-shaped tube filled with a liquid (usually mercury or water) used to measure pressure differences.

2. **Identifying the Function**: The primary function of a manometer is to measure the pressure exerted by a liquid or gas. It does this by balancing the pressure of the liquid in one arm of the U-tube against the pressure in the other arm.

3. **Analyzing the Options**: The question provides four options regarding what a U-tube manometer is used for:
- 1. To measure applied by liquid direction
- 2. To measure density of liquid
- 3. To measure liquid pressure
- 4. To measure liquid volume

4. **Evaluating Each Option**:
- **Option 1**: Measuring the direction of liquid flow is not a function of a manometer.
- **Option 2**: While density can be related to pressure measurements, a manometer does not directly measure density.
- **Option 3**: This option states that the manometer is used to measure liquid pressure, which aligns with the primary function of the U-tube manometer.
- **Option 4**: Measuring liquid volume is not the purpose of a manometer.

5. **Conclusion**: Based on the analysis, the correct answer is option 3: "to measure liquid pressure".

**Final Answer**: The U-tube manometer is used to measure liquid pressure (Option 3).

---