Calculate extension by subtracting original length from stretched length.

In the subtopic Required practical: force and extension, this learning objective focuses on calculate extension by subtracting original length from stretched length. For AQA GCSE Physics 8463 Unit 4.5 Forces, keep the explanation inside Required practical: force and extension and Forces and elasticity. Approved keywords for this objective include extension. A strong answer separates scalar and vector quantities, uses correct units where quantities are involved, and links the physical reasoning back to calculate extension by subtracting original length from stretched length. This is not a generic revision point: it is specifically about Required practical: force and extension, Forces and elasticity, and the approved wording of the learning objective.