Coding classes in Merthyr Tydfil

The span in the model is invented at 14 metres; the record does not give one. Every material has a coefficient of thermal expansion: the fraction of its length it grows for each degree of warming. For cast iron a typical value is about 10.5 millionths per degree. Growth equals that coefficient times the length times the temperature change, and the learner codes it in one line of Python, then runs it for different seasons. Numbers this small are a good reason to learn standard form.

A few millimetres sounds trivial, but it matters if the iron cannot move. Held rigidly at both ends, the span cannot grow, so it pushes, and the push per square metre equals the stiffness of the iron times the growth it has been denied. For a 40 degree rise the model gives about 42 megapascals, roughly the weight of 430 kilograms pressing on every square centimetre. Designers either let structures slide on bearings, leave gaps, or make them strong enough to take the load.

Early tramroads were built from short iron plates, each less than a metre long, so each gap only had to absorb a fraction of a millimetre. Join a kilometre of rail into one continuous length and the free growth would be about half a metre, which is why modern continuous rail is stretched and clamped at installation so it stays in tension rather than buckling. The learner can plot growth against length and temperature and see how the small effect scales.

Asking what happens next, after the first answer, is why a Merthyr Tydfil teenager should keep learning to code in 2026. The longer argument is in why teenagers should still learn to code in 2026.