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Comment by sean-duffy | Hacker News Reader

Is the implication that most humans are comfortable with freefall?

No, the implication is that humans are perfectly comfortable with way more than 1m/s^2, particularly if it is linear and you are comfortably seated.

As an example of Fermi estimation, it's pretty reasonable. 10 m/s is too much, given that most people wouldn't want to spend a lot of time accelerating at the rate of a Corvette on a drag strip. So the correct number is between 1 and 10.

First, we’re talking about a short burst of acceleration, not a multi-day burn on the way to Mars. 1g of lateral acceleration is not a big deal for a few seconds. Most people think it’s fun.

Unfortunately that was actually the least wrong thing about lmm’s comment. We’re not launching a rock, it will not come down as fast as it goes up. And I don’t know what the mixup is around a “receiving railgun”.

Perhaps, though not really. Commercial aircraft generally accelerate at takeoff at around 2-3m/s. For most people, that is quite enough, and that only gets you to 140kt. By comparison, doing 1g for 5 seconds (being generous) only gets you to 95kt. So you aren't really going to be able to get much flight out of that. More realistically, a gun would have to accelerate you to nearly the speed of sound or more. Mannned rocket ships have a (throttled) peak acceleration of 3G, so that sets a realistic upper bound and probably way over what might be considered reasonable. I've read that the Willis tower elevators accelerate downward at 8m/s and that is uncomfortable and just for a short time. It's likely the case that such acceleration would feel better if one were lying down. It's a curious question.

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