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Q: mass density measurement ( No Answer,   2 Comments )
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 Subject: mass density measurement Category: Science > Physics Asked by: lbloom-ga List Price: \$20.00 Posted: 05 Oct 2006 08:44 PDT Expires: 18 Oct 2006 14:50 PDT Question ID: 770999
 ```Is there a method to measure the density of a solid mass, say a pile of sand, using remote sensing?```
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 Subject: Re: mass density measurement From: qed100-ga on 05 Oct 2006 16:54 PDT
 ```To measure mass-density you need to measure both the mass itself, and the volume. It's then just a matter of division: mass/volume. The densities of astronomical objects are measureable. As an example, the volume of planet Jupiter is determinable by measuring its angular size in a telescope, then measuring its distance via trigonometric methods, and therefrom its dimensions can be gotten and then the planet's volume. Knowing how big it is, its mass is then found by measuring both the radius and period of a moon's orbit. This information yields the mass. Here on Earth the masses of large mountains have been estimated. A mountain's volume can be roughly determined by surveying its geometry, and some measure of tis mass can be made at *some* distance by noting the deflection of a plumb-bob from vertical. But doing the same for something such as a mound of sand may be less effective. You could measure its volume at a distance by knowing that distance and noting its angular dimensions, perhaps through a telescope. But its mass would be rather hard to determine by gravitic effects. In this particular case the most effective thing would be to know, by experiment, the mass-density of a typical mound of sand, and plug that into the volume of the target mound. Now here's something I just thought of, though it's a little far-fetched at the moment. If you fire a bullet from a gun into a mound of soil, the rate at which it decelerates as it borrows into the grains will be a function of the bullet's initial energy and the drag imposed upon it by the heap of sand. It's conceivable to design a bullet with a small radio transmitter inside. The muzzle energy of the projectile would be known ahead of time by knowing the bullet's overall design. The transmitter would generate a known base-frequency, which would be monitored with a receiver/recorder. The bullet is fired from a distance into the mound, and the Doppler shift in the frequency recorded. This then could be reduced to the density of the soil.```
 Subject: Re: mass density measurement From: rawbmobile-ga on 13 Oct 2006 09:53 PDT
 ```The volume and density measurements will probably need to be accomplished separately. Volume measurement can be done using a laser profiler (I'm assuming that this pile is on a flat surface). The density measurement can be accomplished using x-ray or gamma ray measurement depending upon the material in question. It might be possible to combine both measurements using xrays but then the xray device may become prohibitively expensive if it must also image and not just be used for a density measurement. If it is known a head of time what possible constituents are in the "pile of sand" then the detection techniques can be refined.```
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