Experienced cooks can tell whether an egg is raw or hard boiled by rolling it down a slope. how is this possible? What are they looking for?

 Answer: Experienced cooks can tell whether an egg is raw or hard boiled by rolling it down a slope. A raw egg has liquid inside it and hard boiled has solid. when raw egg rolls, the liquid tries to force out towards the outer walls which increases moment of inertia I = ∑mr^2 of the egg. But solid i.e boiled egg has less moment of inertia. From principle of conservation of linear momentum,

I⍵ = constant

I 2π/T = constant. It gives I ∝ T

If Ir and Ih are M.I of raw and hard-boiled egg while Tr and Th are corresponding spinning the time period. Since, Ih<Ir, we get Th <Tr. The hard-boiled egg moves faster than the raw egg.