# How to find mass?

Many of us in school time asked the question: "How to find the mass of the body"? Now we will try to answer this question.

**The determination of mass through its volume**

Let's say you have a barrel at your disposaltwo hundred liters. You intend to completely fill it with diesel fuel, which you use to heat your small boiler house. How to find the mass of this barrel, filled with diesel fuel? Let's try to solve this simple at first glance task together with you.

Solve the problem of how to find the mass of matter through its volume, quite easily. To do this, apply the formula for the specific density of matter

p = m / v,

where p is the specific density of the substance;

m is its mass;

v - occupied volume.

As a measure of mass, grams, kilograms and tons will be used. Measures of volumes: centimeters cubic, decimeters and meters. Specific gravity will be calculated in kg / dm³, kg / m³, g / cm³, t / m³.

Thus, in accordance with the conditions of the problem, we have at our disposal a barrel with a volume of two hundred liters. This means that its volume is equal to 2 m³.

But you want to learn how to find mass. From the above formula it is derived as follows:

m = p * v

First we need to find the value of p-specific density of diesel fuel. You can find this value using the directory.

In the book we find that p = 860.0 kg / m³.

Then we substitute the obtained values into the formula:

m = 860 * 2 = 1720.0 (kg)

Thus, the answer to the question of how to find mass,was found. One ton and seven hundred twenty kilograms is the weight of two hundred liters of summer diesel fuel. Then you can just as accurately calculate the total weight of the barrel and the capacity of the rack under the barrel with the solar bar.

**The determination of mass through density and volume**

Very often in practical tasks in physicsyou can find such quantities as mass, density and volume. In order to solve the problem, how to find the mass of the body, you need to know its volume and density.

Items that you will need:

1) Measuring tape.

2) Calculator (computer).

3) Capacity for measurement.

4) Ruler.

It is known that in subjects with an equal volume, butmade of different materials, there will be a different mass (for example, metal and wood). The masses of bodies that are made of a certain material (without voids) are directly proportional to the volume of the objects under consideration. Otherwise, the constant is the ratio of mass to volume of objects. This indicator is called the "density of matter". We shall denote it by the letter d.

Now we need to solve the problem of how to find the mass in accordance with the formula d = m / V, where

m is the mass of the object (in kilograms),

V is its volume (in cubic meters).

Thus, the density of a substance is the mass of a unit of its volume.

If you need to find the density of the material from which the object was created, you should use the density table, which can be found in the standard textbook on physics.

The volume of the object is calculated by the formula V = h * S, where

V - volume (m³),

H - height of the object (m),

S - the area of the base of the object (m²).

In the event that you can not clearly measuregeometric parameters of the body, then you should resort to the help of Archimedes' laws. To do this, you will need a vessel that has a scale for measuring the volume of liquids and drop the object into water, that is, into a vessel on which there are fissions. The volume to which the contents of the vessel will be increased is the volume of the body that is immersed in it.

Knowing the volume V and the density of the object d, you canIt is easy to find its mass by the formula m = d * V. Before calculating the mass, it is required to bring all the measuring units into a single system, for example, into the SI system, which is an international measuring system.

In accordance with the above formulas, you canto draw the following conclusion: to find the required mass value with a known volume and known density, it is required to multiply the value of the density of the material from which the body is made by the volume of the body.