………….. Errors arise on account of shear……………… of the ………….. .

Answer

To solve the question, we need to identify the type of errors that arise due to a specific cause. The question mentions "shear" and "the observer," which leads us to consider the types of errors in measurements.

### Step-by-Step Solution:

1. **Understanding Errors**:
- Errors in measurements can occur due to various reasons. They can be classified into three main types: systematic errors, gross errors, and random errors.

2. **Defining the Types of Errors**:
- **Systematic Errors**: These are consistent and repeatable errors that occur due to a flaw in the measurement system or environmental factors. They can often be corrected.
- **Gross Errors**: These errors arise from human mistakes or carelessness, such as misreading instruments or recording incorrect data. They are typically large and can significantly affect the results.
- **Random Errors**: These errors occur unpredictably and can vary from one measurement to another due to unknown factors.

3. **Analyzing the Question**:
- The question specifically mentions "shear" and relates it to the observer. The term "shear" suggests a small amount of carelessness or oversight in the measurement process.

4. **Identifying the Correct Error Type**:
- Since the question refers to errors arising from "shear carelessness," it aligns with the definition of gross errors, which are directly linked to the observer's mistakes.

5. **Final Answer**:
- Therefore, the complete statement is: "Gross errors arise on account of shear carelessness of the observer."