Extension - GCSE Physics Definition

In GCSE Physics, "extension" refers to how much an object, like a spring or a wire, stretches when a force is applied to it. When you pull on a spring, for example, it gets longer. This extra length is called its extension. The extension depends on how strong the force is and the material the object is made from. According to Hooke's Law, for many materials, the extension is directly proportional to the force applied, as long as you don't stretch it too much. Once you release the force, the object usually goes back to its original shape if it hasn't been stretched beyond its elastic limit.