Stretching a spring?

Question

How far can you stretch both a compression spring and an extension spring before breaking it? Both springs are quite small (below 20cm)

Answer 1

There is no simple answer to that. You would have to know the spring material, and even with that, it is difficult to calculate. Spring manufacturers do specify the allowable maximum extension as part of the spring data. Try to find a similar spring (spring diameter, wire diameter, spring length, spring material and spring constant) in a spring catalog and you will get some idea of the maximum stretch.