Which is a suitable method to decrease friction

Options

A. Polishing
B. Lubrication
C. Ball bearing
D. All of these

Answer

To solve the question "Which is a suitable method to decrease friction?", we can analyze the options provided and understand how each method works to reduce friction.

### Step-by-Step Solution:

1. **Understanding Friction**:
Friction is the resistance that one surface or object encounters when moving over another. It is influenced by the nature of the surfaces in contact and the force pressing them together.

2. **Option A: Polishing**:
- **Explanation**: Polishing a surface makes it smoother by reducing its roughness. A smoother surface has fewer microscopic peaks and valleys, which means there is less area for friction to act upon.
- **Conclusion**: Polishing is a method to decrease friction.

3. **Option B: Lubrication**:
- **Explanation**: Lubrication involves applying a substance (like oil or grease) between two surfaces in contact. This lubricant creates a film that separates the surfaces, reducing direct contact and thus decreasing friction.
- **Conclusion**: Lubrication is also a method to decrease friction.

4. **Option C: Ball Bearings**:
- **Explanation**: Ball bearings consist of smooth balls that roll between two surfaces. This rolling motion reduces the area of contact compared to sliding, which significantly decreases friction.
- **Conclusion**: Ball bearings are a method to decrease friction.

5. **Final Conclusion**:
Since all three methods—polishing, lubrication, and ball bearings—effectively reduce friction, the correct answer is that all of these options are suitable methods to decrease friction.

### Final Answer:
All of the above methods (polishing, lubrication, and ball bearings) are suitable to decrease friction.

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