At the solution of physical tasks often it is required to transfer physical quantities from some systems of measurement to others. As a rule, this process does not cause special difficulties. Units of measure of uniform physical quantities are connected among themselves by the corresponding coefficients (occasionally, simple formulas). However, in practice sometimes it is necessary to work with diverse sizes and to transfer, for example, kilograms to cubic meters
It is required to you
- calculator
Instruction
1. To transfer the known number of kg to cubic meters, learn density of substance for which a transfer is made. For this purpose find the corresponding table of density of substances. For convenience of calculations density of substances in such table has to be specified in kilograms cubic meter (kg/m³). It is standard unit of measure of density in IS (international system).
2. Having determined substance density by the table, use the following formula: Kmk = Kkg / P, where: Kmk – the number of cubic meters, Kkg – the number of kg (kilograms), P – the substance density expressed in kg/m³.Пусть, for example, is required to calculate what volume (how many cubic meters) will occupy 10 tons (10,000 kg) of a terrace board. Decision: We find (in the Internet) density of a terrace board. It makes 800 kg/m³. Having used the above-stated formula, it is possible to calculate that the number of cubic meters will be: 10000 / 800 = 12.5
3. Often happens so that it is difficult to determine substance density by tables. For example, the necessary table it can not appear near at hand or the name of substance is unknown. Sometimes objects can consist of several materials united in an unknown proportion at once. And, even density of the known substance (material) can change over a wide range (for example, density of wood depends on its humidity).
4. If it was not succeeded to determine substance density by the table, then measure it independently. For this purpose (whenever possible) separate a piece of material, it is desirable the correct form and count its volume in cubic meters. So, for example, if it is boards, then saw off exactly approximately half-meter piece of a board. Then measure (in meters) length, width and thickness of a sample. Multiply these numbers – the received work will be volume. Now weigh a scrap of a board and divide its weight (in kg) into earlier calculated volume (in m³). The received number will equal board density in kg/m³.
5. If it is necessary to transfer the known number of kilograms of water or weak solutions of other substances to cubic meters, then density of liquid it is possible to accept equal 1000 kg/m³. The same value of density can be used also at rough (estimated) calculations of volumes of other liquids. To receive exact value of density of liquid, cast a part of liquid in a measured cylinder or fill with it capacity with in advance known volume. Then, weigh the container with liquid and divide its weight (without container weight) into volume. Do similar manipulations to receive density of loose substance.