Choose the correct statement

Options

A. Friction force always opposes the motion of the body
B. The direction of the force of friction always opposes the tendency of relative motion of a body
C. The coefficient of kinetic friction is usually grater than the coefficeint of static friction
D. Friction force depends on the surface area of contact

Answer

To solve the question of choosing the correct statement regarding friction, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement 1: "The friction force always opposes the motion of the body."**
- Analysis: This statement is misleading. While it is true that friction opposes the relative motion between surfaces, it is not correct to say that friction always opposes the motion of the body. Static friction can prevent motion, but kinetic friction acts on moving bodies and opposes their relative motion.
- Conclusion: **False**

2. **Statement 2: "The direction of the force of friction is always opposite to the tendency of relative motion of the body."**
- Analysis: This statement is accurate. Friction acts to oppose the relative motion between two surfaces. For example, if a wheel is rolling forward, the friction force acts backward to oppose the tendency of the wheel to slip backward.
- Conclusion: **True**

3. **Statement 3: "The coefficient of kinetic friction is usually greater than the coefficient of static friction."**
- Analysis: This statement is incorrect. The coefficient of static friction is generally greater than that of kinetic friction. Static friction must be overcome to initiate motion, and once in motion, kinetic friction takes over, which is usually less.
- Conclusion: **False**

4. **Statement 4: "The friction force depends on the surface area of the contact."**
- Analysis: This statement is also false. The force of friction does not depend on the surface area of contact between the two surfaces. It primarily depends on the normal force and the nature of the surfaces in contact.
- Conclusion: **False**

### Final Answer:
The correct statement is **Statement 2**: "The direction of the force of friction is always opposite to the tendency of relative motion of the body."

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