With increase of temperature, the frictional force acting between two surfaces

Options

A. increases
B. decreases
C. remains same
D. none of the above

Answer

To solve the question regarding the effect of temperature on the frictional force acting between two surfaces, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Friction**: Friction is a force that opposes the relative motion between two surfaces in contact. It depends on the nature of the surfaces and the normal force acting between them.

2. **Effect of Temperature**: When the temperature of a material increases, the kinetic energy of its particles also increases. This leads to thermal expansion, where the distance between the particles of the material increases.

3. **Surface Smoothness**: As the temperature rises and the material expands, the surfaces in contact may become smoother. This is because the microscopic irregularities on the surfaces can be reduced due to thermal effects.

4. **Coefficient of Friction**: The coefficient of friction (μ) is a measure of how much frictional force exists between two surfaces. With an increase in temperature, the coefficient of friction typically decreases because the surfaces are smoother.

5. **Frictional Force Calculation**: The frictional force (F_friction) can be calculated using the formula:
\[ F_{\text{friction}} = \mu \cdot N \]
where \(N\) is the normal force. Since the coefficient of friction decreases with an increase in temperature, the overall frictional force will also decrease.

6. **Conclusion**: Therefore, with an increase in temperature, the frictional force acting between two surfaces decreases.

### Final Answer:
With an increase in temperature, the frictional force acting between two surfaces decreases.

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