--- In spacesettlers@yahoogroups.com, "Victor Smith" wrote:
> From: hitssquad
>> foundation piles [...] might have to be driven six times as deep as they would on Earth.
> Seems to me, that the way to keep your forklift from tipping over [...] is NOT to increase your height by six times

Straw man, and a 6x-normal-height forklift would be 36x as tippy on the moon.

If the strength of gravity felt at Earth's surface could be reduced to 1/6th, while changing nothing else, speed-limit signs would have to be changed to 1/6th, like so:

60 mph --> 10 mph
45 mph --> 7 mph
35 mph --> 6 mph
30 mph --> 5 mph
25 mph --> 4 mph

60-to-0 stopping distances would be 6x as far.
0-60 mph acceleration times would be 6x as great.
Cornering g-forces would be 1/6th as great.
Track times would be 6x as great.
The value of human labor would be 1/6th.

From: hitssquad

> The value of human labor would be 1/6th.

Reductio ad absurdum: If this linear, direct relationship were valid, then astronauts on space stations would have zero productivity. Therefore, this relationship can't be linear.

I think there's a little something to what you're saying, but that you're overstating your case. And I think what you're saying only points to the idea that ensuring good productivity in low and zero gravity environments will require a bit of engineering work. I think most everyone would agree with that proposition.

I think you're also ignoring the possibility that low and zero gravity might, in certain cases, be a productivity booster. I know that Gerard O'Neill viewed 0-G in particular as a productivity booster. I would agree, assuming:
a) A bit of engineering work to sensibly deal with certain aspects of zero G
b) That in orbit, centrifugal force enables us to have it both ways; we can have spin gravity where it helps, and 0-G where that might turn out to help

Regards,
Mike Combs

On Fri, Apr 19, 2013 at 12:20 AM, hitssquad wrote:
(...)
> If the strength of gravity felt at Earth's surface could be reduced to
1/6th, *while changing nothing else*, speed-limit signs would have to be
changed to 1/6th, like so:
(...)

My problem with your line of argumentation so far is this insistence in
"changing nothing else". Of course people living in low-g environments, if
that ever happens, should and will change everything.

For instance, at 1/6 g, flight would be much easier, and perhaps people
would not even use land cars; no need to change speed limit signs then.
Also, in cases were heavy cargo is needed, you would have far more freedom
to construct 3D structures, and then perhaps transport tubes and suspended
rails would be preferred to 2D roads. By the way, a three-dimensionalized
city would in principle present economies in distance, time and energy, for
everything would be organized volumetrically instead of over a plane;
hence, everything would be closer.

The formula for stopping distance is

Kinetic Energy = 0.5 * mass * velocity^2

So we can see that if mass is halved then the stopping distance is halved.

Separately the relationship between velocity and Kinetic Energy is not linear. So if you cut your velocity in half your stopping distance is cut to 1/4 of the distance.

On human labor there is far more factors than just gravity when figuring human labor values.

Brooks

--- In spacesettlers@yahoogroups.com, "hitssquad" wrote:

On 4/18/13 9:20 PM, hitssquad wrote:

> If the strength of gravity felt at Earth's surface could be reduced to
> 1/6th, while changing nothing else, speed-limit signs would have to be
> changed to 1/6th, like so:
>
> 60 mph --> 10 mph
> 45 mph --> 7 mph
> 35 mph --> 6 mph
> 30 mph --> 5 mph
> 25 mph --> 4 mph
>
> 60-to-0 stopping distances would be 6x as far.
> 0-60 mph acceleration times would be 6x as great.
> Cornering g-forces would be 1/6th as great.
> Track times would be 6x as great.
> The value of human labor would be 1/6th.

Utter rubbish.

If we ever meet on the moon, please let me smack you -- I assume you
won't mind, since you believe my arm will move only 1/6 as fast and hurt
1/6 as much.

How fast was the Lunar Rover?

The answer is: faster than 4 MPH. It was in fact 8 MPH, and hit 11.2 MPH at one point. Designed and built in the 1960s.

I suspect that we can do even better with five decades between then and the early 2020s. And when the 2030s get here, oh wow.