Classify the following amongst contact and non contact forces :
frictional force

Explanation

### Step-by-Step Solution:

1. **Understanding Forces**: First, we need to understand the two categories of forces: contact forces and non-contact forces.

2. **Definition of Contact Forces**: Contact forces are those that require physical contact between two objects. Examples include friction, tension, and normal force.

3. **Definition of Non-Contact Forces**: Non-contact forces act at a distance without the need for physical contact. Examples include gravitational force, magnetic force, and electrostatic force.

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