Why is there a proportional relationship between the extension of a spring and the weight on it?
Proportionality between two variables just means that when one of the variables is increased or decreased, so is the other variable. Proportionality is very unspecific and doesn’t crave a linear relationship or anything fancy like that. One variable could double whilst the other one quadrupled (just an example). Key point is that the change in size of two or more variables that are said to be proportional, must be of same sign. So why is there a proportional relationship between the extension of a spring and the weight on it? When you increase the load on a spring by adding more mass (increasing the weight “gravitational pull” on the spring), the spring is stretched (extended) until the spring has built up enough tension to keep itself from extending further. The tension force increases when the extension increases. When the weight on the spring is increased the force pulling on the spring is increased extending the spring. When the spring is extended the tension or force of the spring
