Tip 1: How to find the density of the body

In addressing some of the physical tasks required to find density body .Sometimes the density of the physical body is necessary to define in practice, for example, to find out whether or not it will sink.Incidentally, the human body can also be attributed to physical bodies.Moreover, the concept of "density" of the human body has long been part of everyday life.So "stout" man is commonly called "dense", and someone who has the opposite body constitution - "loose."
you need
• calculator, scale, ruler, measuring cups, table-density substances.
Guide
1
to find the density of the physical body, determine from a substance or material it is.Then take the table and find the density of matter in it the substance.For example, if the object is made of aluminum, its density is equal to 2.7 g / cm³.
2
If the body is composed of several substances, get in the relevant tables the density of each of them.To find the density of the body as a whole, determine the contribution of each substance in
the formation of the density of the object.To do this, determine the volume or mass of each of the homogeneous, and then calculate the mass and volume of the body.
3
Suppose, for example, the body consists of two parts mass m1 and m2, respectively.The density of each part - ρ1 and ρ2.To find the average density of the body, find the total volume: V = V1 + V2 = m1 * ρ1 + m2 * ρ2, and then divide the total weight of the body (m = m1 + m2): ρ = V / m = (m1 * ρ1 +m2 * ρ2) / (m1 + m2), where: V - total body;
V1 and V2 - the volume of the first and second parts of the body, respectively;
m - total weight;
m1 and m2 - mass of the first and second parts of the body, respectively;
ρ - the average density of the body;
ρ1 and ρ2 - the density of the first and second parts of the body, respectively.
4
If known volumes (V1 and V2) of each body part, as well as their density, for calculating the body density, use a similar formula: ρ = V / m = (V1 + V2) / (m1 + m2) = (V1 + V2) / (V1 / V2 + ρ1 / ρ2).Designations are the same parameters as in the previous formula.
5
If the material (substance), of which the body is unknown or has a variable density (for example, wood density depends on humidity) to find its density, determine the scope and divide by the mass.That is, use the formula: ρ = V / m.Dlya this, of course, have to calculate or measure the volume and mass of the body, but this method will give the most accurate result.If the body is shaped like a simple geometric shape, calculate its volume by using the corresponding formulas of solid geometry.The amount of complex bodies define the terms of the volume of liquid displaced.Body weights get by weighing.

Tip 2: How to determine the density of the body

Density is the mass of a substance per unit of its volume.Any physical body can be considered as a substance that is in a solid state.Is the density adopted by the Greek letter ρ.
you need
• - a subject which you want to calculate the density;
• - scales;
• - dimensional dishes;
• - measuring instruments.
Guide
1
Determine the mass of the body.Use of weights for accuracy class which corresponds to the required accuracy.For weighing very small items can use the pharmacy scales.If the object is large, fit a regular store scales.
2
Measure the volume of the body.Remember mathematical formulas are used to calculate the volume of various geometric bodies.To calculate the volume of a cube you only need to measure one facet, and tell the resulting size of the third degree.To find the volume of the box, measure the length, width and height and multiply them.Prism (direct and oblique) and a box: In the prism volume V is equal to the product of the square base and the height, that is V = S * h.In a regular pyramid and a direct product of the area of ​​the cone base and the height must be divided by 3.
3
body may be irregularly shaped.Look, if his mind can not be divided into several parts, with the shape of regular geometric bodies.If so, perform the necessary measurements, calculate the volume of all parts and add the results.This will be the amount of the original body.
4
at work and at home often have to deal with the bodies that can not be divided into separate fragments of the correct form.In this case, use the law of Archimedes.Pour the water into a measuring vessel, so that the top left area.Determine how much in a vessel of water and drop in a body.See how increased volume of the contents of the vessel.Subtract the second figure first.According to Archimedes' principle, the volume of the body and the water it displaces is equal.
5
Calculate the density of the material from which the body is composed.To do this, you already know the mass divided by the volume, that is, ρ = m / V.If the body is made up of a pure substance, you can identify any of it.To do this, find the result in a table of densities.