Amen! All praise SI, keeping science simpler since 1960!
--- On Mon, 24/5/10, constantine_thomas_uk <> wrote:
From: constantine_thomas_uk <>
Subject: [Traveller_TNE] Re: Volume:Mass for asteroid
To:
Date: Monday, 24 May, 2010, 4:18
This is why I don't screw around with "grams per cubic centimetre" - keep it all SI, kilograms per cubic metre makes so much more sense :). It means that one cubic metre of metal has a mass of 7,900 kg, so 10 cubic metres would therefore have a mass of 79,000 kg.
Though remember that 10 cubic metres is NOT the same as a 10x10x10 metre cube, which has a volume of 1000 cubic metres and therefore a mass of 7.9 million kg (7,900 * 1,000, right?)
--- In , daryl@... wrote:
>
> Oooops
>
> I think I did my calculations wrong, then.
>
> I was thiking (for the more dense material) of 7.9 grams per cm3 being equal to 7.9 kg per 10 m3.
>
> (Just multiplying each by 1,000)
>
> But I think I did the basic math wrong. Let me try that again.
>
> 7.9 grams * 1000 = 7900 grams = 7.9 kg
>
> 1 cm3 * 1000 = 10 m3
>
> Wait, what am I missing?
>
>
> Sent on the TELUS Mobility network with BlackBerry
>
> -----Original Message-----
From: "constantine_thomas_uk" evil_dr_ganymede@...
Date: Sun, 23 May 2010 17:34:11
Subject: [Traveller_TNE] Re: Volume:Mass for asteroid
>
> Oh nvm, found it:
>
> > Hey all. Anyone know what an acceptable Volume to Mass ratio would
> > be for an asteroid? I realize it varries substancially based on what
> > kind of ore is in it, but I was just wondering what an average might
> > look like. (Kinda like how cargo is assumed to be 1:1 by default,
> > unless specified otherwise.)
>
> Far Trader is mostly right. When it comes to materials, asteroids are generally either rocky or metallic, so you'd expect density to be about 3300 kg/m³ for the rockies or about 7900 kg/m³ for the metallics.
>
> However, a lot of asteroids seem to be "porous" in that they have lots of spaces inside them, probably because they are actually "rubble piles" - lots of smaller bodies held together by their very low gravity and covered in a surface layer of dust. This 'porosity' decreases the density significantly, pushing it down to as low as 1300 kg/m³ for a porous rocky asteroid. Ice can lower the density too, but if an asteroid contains a lot of ice then it's probably better to call it a cometary body.
>