Springs and load-extension graphs
Learn how to measure spring extension, plot a load-extension graph, recognise when a proportional pattern ends, and use the spring constant in Supplement / Extended questions. This is Cambridge International IGCSE Physics 0625, separate from Egypt’s Egyptian Baccalaureate / Thanaweya Amma and not a Year 3 course.
A spring changes shape when a force pulls it
A hanging load pulls down on a spring and makes it longer. An elastic solid returns to its original shape and size when the force is removed, provided it has not been stretched too far. Do not assume every material behaves elastically for every size of force.
Open the worked example
Stretch a small spring gently, then remove the load. If it returns to the same length, it has behaved elastically in that test.
Quick check: What should happen to an elastic spring when its load is removed?
Think, then reveal: It returns to its original shape and size, as long as it was not stretched beyond its elastic behaviour.
Explore a load-extension graph
Interactive graph · choose a load
These are the example readings printed in Volume A, not new experimental measurements. Move the control to highlight a point on the load-against-extension graph.
Straight region: k = F ÷ x = 2 N ÷ 4 cm = 0.50 N/cm.
Source example: original length 10 cm; loaded lengths 12, 14, 16, 18, 20 and 23 cm for loads 1–6 N. The blue straight section joins the proportional readings; the final red point shows that the pattern has changed. The graph is a learning model built from those readings.
Practise, then read the explanation
Try each question first. The tier label shows whether it is Core or Supplement / Extended. Open a hint if needed, then submit to see why the answer works.
Optional hint
Extension is the increase in length, not the full stretched length.
Original learning material aligns to Cambridge IGCSE Physics 0625 syllabus objectives 1.5.1.2 (Core), 1.5.1.9 and 1.5.1.10 (Supplement / Extended) as grouped in the supplied Volume A. It teaches elastic solids, original length and extension, the load-extension experiment and graph, the limit of proportionality, and spring constant. Source reading: Physics-0625 Volume A, PDF pp. 64–70 (printed pp. 56–62). The graph activity reproduces the source example readings and is not a physical measurement.