Friction is a/an

Options

A. self-adjusting force
B. necessary evil
C. important force in daily life
D. all of the above

Answer

**Step-by-Step Solution:**

1. **Understanding Friction**: Friction is a force that opposes the relative motion between two surfaces in contact. It plays a crucial role in our daily activities.

2. **Analyzing the Options**:
- **Option 1: Self-adjusting force**: Friction can adjust itself based on the applied force. For example, if a force of 1N is applied to a block, the static friction will also be 1N to prevent movement. If the applied force increases, the static friction will adjust accordingly until it reaches its maximum limit.

- **Option 2: Necessary evil**: Friction is essential for many activities, such as walking or driving. However, excessive friction can reduce the efficiency of machines, making it a "necessary evil." Without friction, we would slip and be unable to perform tasks effectively.

- **Option 3: Important force in daily life**: Friction is vital for everyday activities. It allows us to walk without slipping and helps vehicles to grip the road. Without friction, we would struggle to perform basic tasks.

3. **Conclusion**: Since friction is a self-adjusting force, a necessary evil, and an important force in daily life, we can conclude that all the options provided are correct.

4. **Final Answer**: Therefore, the correct answer is **Option 4: All of them**.

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