Since Khandro doesn't seem to be around Tilly - if you take an egg, put it on a flat surface and spin it, it will manage about one rotation. If you take a hard-boiled egg and spin it in the same way it will spin for ages. An easy way to tell if an egg is hard-boiled or not before you throw it at someone.
Thanks, bhg. I see the physics in that now. I've never tried it though because, usually, if I hard boil an egg, I eat it......with lots of lovely buttered toast.
Ah, we tend to boil half-a-dozen at a time when we're camping and take one a day out to eat at lunchtime. I ALWAYS spin them before I crack them to shell them.