Specific weight is the weight of unit of volume of substance. To learn to calculate specific weight very simply, mathematically this size is equal to the work of density on acceleration of gravity or to the weight relation to volume.
It is required to you
- - areometer;
- - oblong glass vessel;
- - ""Eureka"";
- - textbook in physics;
- - calculator.
Instruction
1. The size of specific weight depends on the place of measurement therefore it is not either physical, nor chemical characteristic of substance. Roughly speaking, it is the gravity of unit of volume. Often use this concept in the analysis of a state and type of soil or a stone of the construction purposes, when carrying out sewer and heating pipes and so forth.
2. It is possible to determine the specific weight of a solid body by the way of replacement opened by Archimedes. At the same time an object is located in liquid with a single density, and for measurement the special device "Eureka" which shows the volume of the forced-out water is used, thereby giving value of its weight. Then the specific weight of a body is equal to the relation of its body weight to weight of the forced-out water.
3. Specific weight of liquid it is easy to measure by means of the device under the name the areometer. It represents a glass tube which is soldered since both ends, with a glass ball on the end. The ball is filled with small fraction, and in the top part of the areometer the scale with values of specific weight and degree of test solution is put.
4. Devices differ depending on what type of liquid (it is easier or heavier than water) is analyzed. In the first case of division of the device begin with 1 and are counted down, i.e. towards reduction. If liquid it is heavier than water, then the scale is conducted in the opposite direction, from 1 up, on increase.
5. Remember that the specific weight of liquid changes depending on its temperature. Therefore on each areometer the normal temperature at which measurement will yield the most correct result is given. Bring liquid to this temperature and if there is an opportunity, then and the room in which experiment is conducted.
6. Pour liquid in a glass cylindrical vessel not less than a halfliter and 20-25 cm high. Carefully lower in it the areometer and do not take away a hand, do not make sure yet that he swims independently. Wait until the device and level of liquid calm down, at the same time the areometer should not concern walls and a bottom of a vessel. Record the division displayed on a scale and write down value of specific weight.
7. It is possible to calculate specific weight at the solution of tasks and without use of special devices. in this case formulas will be useful. Their of everything two: this relation of weight to the volume occupied by him or the work of density of substance on acceleration of gravity. The used sizes can be found on the basis of own formulas depending on a condition of a specific objective.