Le 15-02-22 16:09, Doctor John a écrit :
> On 22/02/15 19:28, Alain wrote:
>>
>> The 10^-9 range is for our spacial neigourhood, or relatively close to a
>> star. As you travel farther, it drops conciderably. Between the Sun and
>> Proxima Centaury, the vacuum around the moon looks like high pressure.
>>
>> In space, to have a drag equivalent to 100 Km/h on a road, using the
>> 10^14 factor for Earth region, you would need to travel at over 100 000
>> 000 000 000 Km/h (10^16 Km/h). That's  /way/ faster than the speed of
>> light ! (about 10^9 Km/h)
>>
>>
>>
>> Alain
>
> How the hell did you calculate that? I'm not saying you're wrong -
> you're probably right - but can I see the equations?
>
> John
>

The speed of light is a little under 300 000 Km/s. Multiply that by 
3600, the number of seconds in an hour, gives about 1 080 000 000 Km/h 
whitch is somewhat larger than the true speed of light in a vacuum, that 
I rounded down: 10^9

Next, I used the appriximative presure ratio between sea level and space 
"vacuum" in Earth vicinity: 10^14 to 1.
Finaly, I multiplied that with a speed of 100 Km/h (about 60 Miles per 
hour), or highway speed: 10^16

That's around 10 000 000 times the speed of light! In StarTreck second 
generation universe, that's warp 7, or a ludicrous warp 10 millions in 
the original.

As I'm only concerned with the order of magnitude, the approximations 
are acceptable.

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