Advice 1: How to find the mass, knowing the density

In physical and practical challenges often encountered such quantities as mass, density and volume. Of course, to find the mass, knowing the density, you must know the volume of a body or substance. However, sometimes the volume of the object is unknown. In such cases it is necessary to use indirect data or to measure the volume yourself.
How to find the mass, knowing the density
You will need
  • a calculator or computer, a ruler, tape measure, measuring device
Instruction
1
To find the mass , knowing the density, divide the volume of a body or substance to its density. That is, use the formula: m = V / ρ where:V – volume,
ρ is the density,
V is the volume.Before the calculation of the mass bring all units into one system, for example, in the international system of measurement (SI). To do this, turn the volume in cubic meters (m3) and the density in kilograms per cubic meter (kg/m3). In this case, the value of the mass obtained in kilograms.
2
If density and volume are given in one system of units, then pre-translate in C to produce optional. The mass of a body or substance in this case is measured in the unit of mass that is indicated in the numerator of the density units (units of volume in the calculation will be reduced).
For example, if the volume is specified in liters, and the density in grams per liter, the calculated weight obtained in grams.
3
If the volume of the body (substances of) unknown or not specified clearly in the conditions of the problem, then try to measure, calculate or learn using indirect (secondary) data.
If the substance is granular or liquid, it typically is in the tank, which usually has a standard size. For example, the volume of the barrel is usually equal to 200 liters, the volume of the bucket is 10 liters, the volume of glass – 200 ml (0.2 liters), the volume of a tablespoon is 20 ml, the amount of a teaspoon – 5 ml. On the volume of three-liter and one-liter jars you might guess from their names.
If the liquid is not the entire capacity or the capacity of the non-standard, then pour it into another container, whose volume is known.
If a suitable container, pour the liquid using measuring cups (cans, bottles). In the process of skimming liquids just count the number of cups and multiply by the volume measuring containers.
4
If the body has a simple shape, then calculate its volume using the appropriate geometric formula. For example, if the body has the shape of a rectangular parallelepiped, then its volume will be equal to the product of the lengths of its edges. That is:V [PR].couples. = a*b*c where:V [PR].couples. – the volume of a rectangular parallelepiped, and
a, b, c - values of its length, width and height (thickness), respectively.
5
If the body has a complex geometric form, then try the (relatively!) break it down into a few simple parts, find the volume of each of them separately and then add up the resulting values.
6
If the body cannot be divided into more simple shapes (e.g., a statue), then use the method of Archimedes. Lower the body into the water and measure the volume of displaced fluid. If the body does not sink, then "push" it with a thin rod (wire).
If the volume of the displaced body of water is problematic to calculate, then weigh the resulting water, or find the difference between initial and remaining mass of water. At the same time, the number of kilograms of water will equal the number of liters, the number of grams of the number of milliliters, and the number of tons quantity cubic meters.

Advice 2: How to find the volume of the barrel

It was difficult to understand why the old barrels had such "big-bellied" form. It's not in the delights of the ancient designers. In principle, this would fit and capacity of the truncated-conical in shape and easier to collect and the amount of such barrels are easy to find. But it is unlikely that barrel was far to drive...
How to find the volume of the barrel
You will need
  • - the range;
  • calculator;
  • - twine.
Instruction
1
Before you calculate the volume of the barrel, carefully inspect it. Modern barrels areusually manufactured industrially. So they have a standard volume that is certainly somewhere specified. The capacity of the barrel (or its contents) can also be found in accompanying documents (waybills, invoices, etc.).
2
In some cases, the volume is easier to determine experimentally. To do this, take a bucket of known capacity and just fill the barrel with water, counting the number of buckets. If some of the water from the last bucket will not fit in the barrel, measure the amount of "extra" water liter jar and subtract from the total volume, obtained by measuring the buckets.
3
Most modern metal and plastic casks are cylindrical in shape. To find the volume of this barrel, measure its height and diameter. Try to measure the internal diameter of the barrel, if you are interested in the capacity of barrels, and not how much space the barrel is in the cellar. Then, multiply the height of the barrel (in meters) by the square of the diameter (in meters) then multiply by the number PI (3,14) and divide by 4. If the barrels much, in advance, divide PI by 4 and multiply the resulting factor by the height and the square of the diameter. As a formula this rule would resemble the following:Vцб = π/4 * D2 * Neely Vцб ≈ 0,785 * D2 * H where:Vцб – the volume of the cylindrical barrel,D – inner diameter of the bottom/cap of the barrel.π is the number PI, approximately equal to 3.14.
4
To measure the diameter of the barrel , take a piece of string and fix one of its ends on the edge of the barrel. Then look at the opposite edge of the barrel most distant point and mark it on the string (for example, tie the knot). Measure the length of string using the ruler or tape measure. Write the result in meters as a decimal. When measuring the height of the barrel problems should arise. However, note that some barrels have a "soaring" bottom, so you need to measure the inner height of the barrel.
5
If the lid of the barrel in any way specify its center (e.g., in the center is a hole for drainage), instead of diameter measure the radius of the barrel. The formula to calculate the volume of the barrel in this case will be the same: Vцб = π * R2 * H where:R is the radius of the bottom/cap of the barrel,
6
If no diameter or radius of the barrel is impossible to measure (e.g., barrels are several "floors"), then determine its "girth" . To do this, take the twine and wrap it around the barrel.Since circumference is calculated by the formula:L = π * D, where: L – the circumference (the circumference) of the barrel,the diameter of the barrel will be equal to the circumference divided by π:D = L / π.This leads to a simple formula:Vцб = L2/4π * Neely Vцб = L2/12,566 * H,
7
To find the volume of this wooden barrels, use a practical formula that applies the majority of winemakers:Vкб = 3,2 * r * R * H where:Vкб – volume classic barrelr is the radius of the bottom/cap of the barrel, R is the radius of the widest part (the middle) of the barrel.
8
So how to measure the radius of the widest part of the barrel is problematic, it is better to use the formula:Vкб = 0,8 * d * D * H. where:d – diameter of the bottom/cap of the barrel, D – diameter of the widest part (the middle) of the barrel.
Is the advice useful?
Search