Force of friction is an example of

Options

A. non-contact force
B. contact force
C. reactive force
D. none of these

Explanation

To determine the type of force that friction represents, we can analyze the definitions and characteristics of the different types of forces. Here’s a step-by-step solution:

### Step 1: Understand the Types of Forces
- **Non-contact forces** are forces that act at a distance without physical contact between objects. Examples include gravitational force and magnetic force.
- **Contact forces** are forces that occur when two objects are in physical contact with each other. Examples include friction, tension, and normal force.

### Step 2: Analyze Friction
- Friction is the resistance that one surface or object encounters when moving over another. It only occurs when there is contact between the two surfaces.

### Step 3: Evaluate the Options
1. **Non-contact force**: This is not applicable to friction since friction requires contact.
2. **Contact force**: This is applicable because friction occurs when two surfaces are in contact.
3. **Reactive force**: Reactive forces, like normal force, act in response to another force. Friction does not always act as a reactive force; it depends on the relative motion of the objects.
4. **None of these**: This option does not apply since we have identified friction as a contact force.

### Step 4: Conclusion
Based on the analysis, the force of friction is best categorized as a **contact force**. Therefore, the correct answer is **B, contact force**.

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