Here's how it works:

* The Spring: The spring inside the scale is calibrated to stretch a specific amount for a given force.

* The Force: When you hang an object from the spring scale, the object's weight (which is a force due to gravity) pulls on the spring.

* The Measurement: The spring stretches, and the scale's markings indicate the amount of force being applied.

Important Note: While spring scales are often used to measure weight, they technically measure the force of gravity acting on an object. The weight of an object is a force, measured in Newtons (N), while mass is a measure of the amount of matter in an object, measured in kilograms (kg).