What are contact forces ? Give examples.

Explanation

### Step-by-Step Solution:

1. **Definition of Contact Forces**:
- Contact forces are defined as the forces that occur when two bodies are in direct physical contact with each other. These forces are only exerted when the objects are touching.

2. **Characteristics of Contact Forces**:
- Contact forces arise from the interaction between the surfaces of two objects. They depend on the nature of the surfaces in contact and the force pressing them together.

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