Define spring constant of spring.

Explanation

### Step-by-Step Solution:

1. **Understanding the Spring Constant**:
The spring constant, denoted as \( k \), is a measure of the stiffness of a spring. It quantifies how much force is needed to stretch or compress the spring by a certain distance.

2. **Hooke's Law**:
According to Hooke's Law, the restoring force \( F \) exerted by a spring is directly proportional to the displacement \( x \) from its equilibrium position. This relationship can be expressed mathematically as:
\[
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