C 8.7 Physics Help Please! Spring Force?

Question

A spring exerts a 20 N force after being stretched by 2.0 cm from its equilibrium length.

By how much will the spring force increase if the spring is stretched from 3.0 cm away from equilibrium to 5.0 cm from equilibrium?

Answer 1

Springs are often assumed to have a linear relationship between the force applied to them and the amount they stretch. So it does not matter from which position you start (at equilibrium or 3 cm away from the equilibrium), but how much distance you cover.

In your case, to cover a 2 cm distance, you need 20 N. If you stretch from 3 cm to 5 cm, you again cover a distance of 2 cm, which means that you need again 20 N.

So the answer to your question is: the spring force will increase by 20 N.