In practical tasks in physics and mathematics such sizes as the volume, weight and density often meet. Knowing density and volume of a body or substance, it is quite possible to find its weight.
It is required to you
- - computer or calculator;
- - roulette;
- - measured capacity;
- - ruler.
Instruction
1. It is known that the objects having the same volume, but made of different materials will have the different weight (tree and metal, glass and plastic). The mass of the bodies made of the same substance (without emptiness), are directly proportional to the volume of the considered objects. In other words, a constant is the relation of mass of a subject to its volume. This size carries the name "substance density. Further we will designate it by letter d.
2. Proceeding from definition, d=m/V, gdem – the mass of a subject (kg), V — its volume (m3). Apparently from a formula, density of substance is a mass of unit of its volume.
3. It is possible to learn density of substance of which the subject is made from the table of density in the annex to the textbook by physics or on the website http://www.kristallikov.net/page15.html where density of practically all existing substances are specified.
4. The volume of a subject can be calculated by a formula: V=S*h, gdev – the volume (m3), S – the area of the basis of a subject (sq.m), H – height of subject (m).
5. If there is no opportunity with an accuracy to perform measurement of the geometrical sizes of a body, use Archimedes's law. For this purpose take the vessel having a scale (or divisions) for measurement of volume of liquid, lower a subject in water (in the vessel supplied with divisions). The volume by which vessel contents will increase - and is the volume of the body shipped in it.
6. If density of d and volume of the V subject are known, it is always possible to find its weight, using a formula: m=V*d. Before calculation of weight bring all units of measure into one system, for example, in the international system of measurement of SI.
7. A conclusion from the given formulas following: to receive required value of weight, knowing density and volume, it is necessary to increase value of volume of a body by value of density of substance of which it is made.