Lubrication reduces friction because

Options

A. Lubricant molecules act as ball bearings
B. Laws of limiting friction are not applicable
C. The relative motion in between solid and liquid
D. Both 1 and 3

Answer

### Step-by-Step Solution:

1. **Understanding Friction**: Friction is the resistance that one surface or object encounters when moving over another. It occurs due to the interlocking of surface irregularities.

2. **Role of Lubricants**: Lubricants, such as oils or greases, are substances that are applied between surfaces to reduce friction. They create a barrier that minimizes direct contact between the surfaces.

3. **Surface Interaction**: When two surfaces are in contact, they have microscopic irregularities. These irregularities can cause resistance to motion. Lubricants fill in these gaps and create a smoother interface.

4. **Formation of Lubricant Layer**: When a lubricant is applied, it spreads out between the two surfaces, forming a thin layer. This layer separates the surfaces, reducing the direct contact area.

5. **Reduction of Friction**: With the lubricant layer in place, the force of friction is significantly reduced because the surfaces are no longer directly interacting. Instead, they slide over the lubricant, which has much lower resistance than the solid surfaces.

6. **Lubricant Behavior**: The molecules in the lubricant can behave similarly to ball bearings, allowing for easier movement between the surfaces. This reduces the energy lost to friction and wear.

7. **Conclusion**: Therefore, lubrication reduces friction because it minimizes the direct contact between surfaces, fills in irregularities, and allows for smoother motion through a lubricant layer.