# Advice 1: How to find the mass, knowing the density and volume

In practical problems in physics and mathematics often such quantities as volume, mass and density. Knowing the density and volume of the body or substance, it is possible to find its mass.
You will need
• - a computer or a calculator;
• roulette;
• - the measuring device;
• - the range.
Instruction
1
As you know, the items that have the same volume but made of different materials will have different mass (wood and metal, glass and plastic). The mass of bodies made of the same substance (without voids), is directly proportional to the volume of the considered objects. In other words, the constant is the ratio of the mass of the object to its volume. This value is called the "density of matter . Further, we denote it with the letter d.
2
From the definition, d=m/V, where
m – mass of object (kg),
V is the volume (m3).
As can be seen from the formula, the density of a substance is the mass per unit volume.
3
To know the density of the material from which made the item from the table of densities in the Annex to the textbook of physics or on the website http://www.kristallikov.net/page15.htmlwhere the density of almost all existing substances.
4
The volume of the object can be calculated by the formula: V=S*h, where
V – volume (m3)
S – area of the base of the object (m2),
H – height of object (m).
5
If you can not accurately measure the geometric dimensions of the body, use the law of Archimedes. To do this, take the vessel, having the scale (or divide) measuring volume of liquid, dip the object in water (in the container, provided with graduations). The volume, which will increase the contents of the vessel, is the volume of the submerged body.
6
If you know the density d and the volume V of the object, you can always find its mass using the formula: m=V*d. Before the calculation of the mass bring all units into one system, for example, in the international measurement system SI.
7
The output of the following formulas is the following: to obtain the desired value of the mass, knowing the density and volume, we must multiply the value of volume on the density of the substance from which it is made.

# Advice 2 : How to find mass if the volume and density

The mass of a body is its most important physical characteristic. In modern physical science, there is a distinction between the concepts of "mass" gravitational mass (as the degree of impact of a body on the earth's gravity) and inertial mass (how much effort will be required in order to bring the body from a state of inertia). In any case, to find the mass very easily, if you know the density and volume of the body.
Instruction
1
In that case, if the body is known to such indicators as the volume (V) and density (p) for calculating the body mass will need to use the formula: m = p*V.
2
For clarity, you can give an example. You want to find the mass of a concrete slab whose volume is 15 m3.
Solution: for finding the mass of the concrete slab is required to know only its density. In order to learn this information, you need to use a table of densities of various substances.
3
According to this table the density of concrete is 2300 kg/m3. Then to find the mass of the concrete slab, you will need to perform simple algebraic action: m = 15*2300 = 34500 kg, or 34.5 tons. Answer: the mass of the concrete slab is 34.5 tons
4
Mass measurement in the traditional way using one of the oldest instruments of mankind - with the help of weights. This is due to the comparison of body weight with the reference weight of cargo weights.
Note
Compute by the above formula, you must realize that in this way is known the rest mass of the body. An interesting fact that many elementary particles have an oscillating mass, which depends on the speed of their movement. If an elementary particle moving with the speed of the body, this particle is massless (e.g. photon). If the speed of motion of the particle below the speed of light, such a particle is called massive.