One of the most important parameters of a physical body - density. By definition density - the scalar size measured for uniform bodies by the body weight relation to its volume. Proceeding from definition it is necessary to understand that density of a body can be removed only for uniform bodies, that is not having cavities. Therefore accounting of cavities in a body is always obligatory, otherwise calculations can be wrong. Of course it does not belong to liquids. The formula for determination of density of a body of r (ro) represents the weight relation to body volume therefore it is important to find these two components.
It is required to you
- - scales
- - 2 graduated cylinders, or measuring tanks
- - glass
- - dynamometer
- - table of the measuring system (MS)
- - table of volumes
- - table of the translation of units
Instruction
1. For a start it is worth determining body weight, for this purpose we use scales. We put a body on scales and we see a quantitative index of body weight measured in kilograms or in grams everything depends on scales and actually body weight. Anyway it is necessary to transfer values of weight to kilograms as it is the main unit in the SI system. If there are no scales that can be defined body weight by a dynamometer. Of course, it depends on actual body weight, if kg m=50, then also the corresponding dynamometer is necessary. The general principle of measurement of body weight in this case is in suspending a body on a dynamometer and to look at its value which is expressed in Newtons, further knowing that for dynamometer stretching on force of 1 N the weight of 102 grams is necessary we count body weight. So, body weight is determined. For determination of mass of liquid it is necessary to measure at first the mass of capacity in which liquid will be poured. After that we pour the studied liquid in capacity and again we put on scales, the difference of mass of container with liquid and tanks without liquid and will be the mass of liquid.
2. We pass to volume. If the body is the correct geometrical figure, then with calculation of volume there will be no problems. If for example the body is a parallelepiped, then we take the table of volumes and we see that V=abc where a, b, c are length, width and height and with ease multiplying sizes we find volume. But there are cases when it is impossible to call a solid geometrically regular therefore for scoping of such body use the following method. Depending on the sizes of a body take a graduated cylinder or other measuring capacity and fill with water, further note the line on the capacity which corresponds to a water maximum in capacity. The studied body undertakes and plunges into water, according to Archimedes's law the volume of a body will be equal to the volume of the forced-out water, we need to measure the volume of the forced-out water. For this purpose we take a glass and we pour water from capacity in a graduated cylinder until water reaches the line noted earlier. We look in a graduated cylinder and we see the water volume which is equal to the volume of our body. To calculate the volume of liquid as easy as shelling pears. It is necessary just to pour it in a graduated cylinder or other measuring capacity, and the result will be obvious. It is necessary to remember, transfer to the SI system, i.e. to transfer the received milliliters or liters to cubic meters, for this purpose we will use the table of the translation of units (http://www.composite.ru/poleznaya_informaciya/table_calculate/).
3. Now there is only a computing part. r=m/v. We divide body weight into the received volume and we receive body density.