Find the work done by the frictional force in drawing a circle of radius r by a pencil of negligible mass with a normal pressing force N ( coefficient of friction `mu_(k)`).

Explanation

To find the work done by the frictional force in drawing a circle of radius \( r \) by a pencil with a normal pressing force \( N \) and a coefficient of friction \( \mu_k \), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Setup**:
- We have a pencil (considered to have negligible mass) that is drawing a circle of radius \( r \).
- The normal force acting on the pencil is \( N \).
- The coefficient of kinetic friction between the pencil and the surface is \( \mu_k \).
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