Sometimes in practice and at the solution of school tasks it is required to find the mass of a cube. To give the correct answer to a similar question it is necessary to specify at first: what is meant "cube". School students usually should find the mass of the real cube, sometimes quite big size. In life, most often mean the weight of one cubic meter of any substance by the mass of a cube.

## It is required to you

- calculator, table of density of substances.

## Instruction

1. To find the mass of a cube as physical body, measure length of an edge of a cube and determine density of substance of which the cube consists. Write down length of an edge of a cube in meters (m), and density in kilograms on cubic meter (kg/m³). For determination of density use the corresponding tables of density of substances. If density of substance is expressed in g/cm³, then for transfer to kg/m³ increase this number for 1000. Then increase substance density by the cube edge dyne built in the third degree. That is use a formula: M = P * P³, where: M – the mass of a cube in kilograms, P – cube density in kg/m³, P – cube edge length in meters.

2. Example. What weight will be had by a cube of ice of 1 cm in size? Decision. We find in tables of density of substances: density of ice equals 0.917 g/cm³. We transfer density and the sizes of a cube to the system of units of measure of SI: 1 cm =0.01m, 0.917 g/cm³=917 kg/m³.Подставляем the received numbers in a formula, we receive: M = 917 * 0.01³ = 0.000917 (kilograms).

3. If the sizes of a cube are unknown and it is difficult to measure them, then determine cube volume. For this purpose place a cube in a measured vessel with water and determine the volume of the liquid which is forced out by it. As an alternative it is possible to determine the mass of the water which is forced out by a cube. The mass of the forced-out water in grams increased by 1000000 will equal to cube volume in m³.Определив the volume of a cube and its density, find its weight on the following formula: M = P * V, where: V – classical designation of volume.

4. If it is necessary just to find the mass of a cube, then, apparently, the mass of cubic meter of any substance is meant. It can do liquid, loose substance or building material (for example, boards). For determination of mass of a cube in this case just specify substance density. The numerical value of density expressed in kg/m³ will also be the mass of a cube in kilograms. At the same time consider that density of water and weak water solutions equals 1000 kg/m³, i.e. the mass of a cube of water equals 1000 kg (one ton).