Hooke’s Law

The negative sign is used because the you pulled an end of the spring in the positive direction and the spring is attempting to move that end back to where it was before you pulled it.

The value of is the distance that an end of the spring has been stretched from its natural or “relaxed” length. It is typical for and if so then the equation simplifies to F=-kx. We wanted you to see the full form first.

k is a constant.