why is used 20ºcelsius as a reference when calculating specific gravity of soil?
607610
I have no idea on the exact reason (was it a committee decision?). However, 20 deg C is room temperature. This is an easy temperature to achieve and it probably really close to the temperature of the lab where they would be taking this measurement. In short, convenience
626920
Trick question! You can figure the VOLUME of dirt you dig up, but without the density of the dirt, you cannot calculate the mass or weight.
757859
haha, k  Draw a picture and draw a free-body diagram.\n\nI don't feel like busting out a paper/pencil  so I'll try it in my mind\n\nF(sub g) cos Theta  =  Mg cos(20 degrees)\n\nbecause the Normal force is equal to the y-component of gravity.\n\nTwo similar triangles, the incline and one which has the Force of gravity straight down, and the y compentn equal opposite of the normal force, and X component equal opposite to F\n\n\nlots of physics i'm skipping in my explanation tho
501191
There is a formula...but this is much easier\n\nhttp://www.onlineconversion.com/temperature.htm
1170472
You've got a couple of strange answers so far.  Look, the formula written above is correct, the mass of the earth is basically the same, but the mass of your surroundings isn't the same.  The pull of gravity is less the higher your elevation, greater the lower the altitude.  If you're on land with higher density, you'll have a greater pull then on land with a lower density.  Pretty much everywhere on land gravity isn't even, out in the middle of the ocean, it's very close to even.  But, keep in mind, these differences are pretty much negligible.  The only way to be able to measure the difference is with scientific equipment.  Actually, it's common practice to measure gravitational anomalies under ice sheets to gleam information about the formations underneath.
753525
that is not enough information, need to know the density of the soil
447698
Surface gravity 273.95 m s-2\n                 (27.9 g)
470314
the specific gravity of water is 1.
833520
There are other scfm definitions. In some cases the reference temperature is 60 degs F. You need to be sure you know there are more than one "scfm"
424828
Soil and climate conditions.
518582
I don't really know, but usually when you're dealing with a coefficient/a ranking based on a known parameter, you have to use a standard item against which to measure. So things like specific gravity are based on an accepted level, and phenolic compounds would be measured against plants widely known to have a certain level.
579919
Draw the triangle with the 20 degree angle.  Put a dot on the hypotenuse to represent the object.  Its mass goes straight down from the spot (gravity).  A perpendicular to the hill through the point represents the resultant.  The horizontal vector connects the bottom of the mass vector to the bottom of the resultant (perp.) vector making a 20-70-90 right triangle.  Tan (20) = horiz/vert (vert = mass) \nso horiz = mass times tan(20)
754995
Nicole I think that to understand what is to be done here I suggest to assume that a coordinate system be attached to one of the objects. I-don’t-remember-who says, but << any reference system at rest or moving with linear constant speed has no privilege with others the like>>.\n(x) m2=4kg is reference system #2, where v2=0, and m1=2kg is moving with speed v=8+12=20 ms, impact by m1 on m2 M1=m1*v=40kg*m/s\n(y) m1=2kg is reference system #1, where v1=0, and m2=4kg is moving with speed v=8+12=20 ms, impact by m2 on m1 M2=m2*v=80kg*m/s, so R=40/80=0.5
608880
And I see that you are no exception, as you HAVE confused them!!\n\nIn the S.I. system, mass is kg, and weight is N (that is Newtons)\n\nIn the Imperial system, mass is slugs and weight is pounds.\n\n1 slug is equal to 14.6 kg.\n1 lb. is qual to 4.5 N\n\nPeople generally confuse them because the authorities decided  to equate 1 kg to 2.2 lb.  Not that it makes that much of a difference if these are used for commercial and not technical/scientific purposes, since gravity is basically the same at all habitable places on Earth.
830453
The terms are similar, but they do differ.\n\nDensity, as usually expressed, is in grams/cubic centimeter-----for example, the element mercury has a density of 13.6 grams per cubic centimeter.Density is non-variable.\n\nSpecific Gravity is a way of relating weights of substances to the weight of water. Therefore, specific gravity, as we measure it, is really specific gravity in the earth's gravitational field at sea level at 0 degrees C.
1007444
Used to convert celcius to fahrenheit and reverse.\n\nF = (9/5 *C) + 32\n\nYeah, I know the parentheses are redundant.\n\nAlso \n\nC = 5/9 * (F-32)\n\nJust to assure yourself and me that the equations are correct\n\n20 degrees Celcius is the same temperature as 68 degrees Fahrenheit.
273737
silica sand spesific gravity is 2.65