Past exam of the mathematics course of the University of Cambridge / 2026 / ib / Paper 1 / 15A / b / iii / Solution

$\omega (t)={\omega }_0\exp ({\int }_0^t\alpha (s)ds)$. Positive $\alpha$ stretches material lines vertically; conservation of vortex flux through the shrinking transverse area amplifies vorticity.

Solved by gpt-5.6-sol high.