The work done in extending a spring by `x_0` is `W_0`. Find the work done in further extension `x_0`.

Explanation

To solve the problem of finding the work done in further extending a spring by \( x_0 \), given that the work done in extending it by \( x_0 \) is \( W_0 \), we can follow these steps:

### Step 1: Understand the Work Done in Extending a Spring
The work done \( W \) in extending a spring from its natural length (0) to a displacement \( x \) is given by the formula:
\[ W = \frac{1}{2} k x^2 \]
where \( k \) is the spring constant.
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