How fast can you spin your arm?
This is a slightly odder one, but again (like the Pope and pizza question ) it stems from a conversation with my friends. This one started from me providing tips to warm up cold hands, an ever-present problem in poorly-insulated student houses. As someone who's quite keen on mountaineering, especially in winter, cold hands are something I think I know about and the engineer in me can't help but try to solve a problem when one is presented. Winter, in case you didn't know what it looked like. (Any excuse to show off some photography...) A classic mountaineer's trick to get some blood flowing in the fingers is to windmill your arm vigourously, both generating some heat through movement and creating some extra artificial blood pressure. This bonus pressure forces some blood into the digits, which can be enough to give you a little more dexterity for a few minutes, handy for undoing zips, putting on crampons etc. While I was keen on the idea, one of my friends put for