Listener Paul got in touch to ask if it's true that there's almost no restriction in the speed an elevator could ascend when it comes to the human body, but that there was a limiting speed for the descent. Graihagh Jackson was perplexed and intrigued by the question and so went to meet engineer, Dr Philip Garsed from Cambridge University to get up to speed...
The first thing to remember is that the speed of the elevator doesn't actually matter. What matters is the magnitude of the acceleration the elevator goes through to get to its top speed. For ascent the acceleration phase pushes you against the floor making you feel slightly heavier. This is usually not too uncomfortable for the passengers. For the descent the acceleration phase actually reduces your weight (you push against the floor less) and if the magnitude of the acceleration is too high you'll become weightless or even be pushed against the top of the elevator. Reductions in weight tend to make people feel sick to their stomach and clearly you can't make people feel weightless or hit the ceiling without causing significant discomfort.