In physics sizes are quantity characteristics of objects and indicators of interactions of bodies among themselves and the environment, for example length, weight, speed, time, corners and so forth. These parameters can be dependent or independent one from another. The relations of many connected sizes are presented in the known formulas from which it is always possible to express any variable.
Instruction
1. Expression of size from a formula is made by means of mathematical operations – transfer of members, division into one number both parts of record, etc. That is, it is necessary to simplify and work with a formula as the algebraic equation. Performing these operations, it is also necessary to consider sign change, rules of a conclusion of size from under a root, exponentiations.
2. In the simplest case in the presence of expression of a type of v = 2*g + 11 for search of size g perform the following operations. Transfer everything the members who are not containing variable g in one (it is better left) a part of this equation, without forgetting to change their sign at transfer for opposite: - 2*g = 11 - v. Transfer other sizes and constants for an equal-sign. If at required size costs coefficient as in this case (-2), divide both members of equation into this constant: g = - (11 – v)/2.
3. At expression from a formula of the size built in degree as, for example, in the following option: S = a*t²/4, perform at first above the described operations. Put a variable in degree on the left side of the equation, and for a constant conclusion from a denominator of fraction increase both parts of a formula by this number: a*t² = 4*S. Divide the equation into a variable and and it will turn out: t² = 4*S/and. To remove degree of a required variable, take a root of the same degree (here square) both from left, and from the right part of expression: t = 4*S/and. Also the reverse situation when required size costs under the sign of a root meets, in this case it is required to execute construction of all equation in the degree specified at a root. So, expression³ √ S = v + will be transformed by g to a type of S = (v + g)³.
4. In the presence of the difficult expressions received as a result of repeated substitutions of various formulas often there are difficulties in expression of unknown size. For example, *f – 15 by search of size k is desirable to carry out preliminary simplification of the equation to designs of a type of S = (√t²*k / (1+g)) by means of introduction of a podstanovochny variable. Accept for x expression in big brackets: x = (√t²*k / (1+g)), then the initial equation will look so: S = x*f – 15. From here easily there is x = (S + 15) / f. Further return instead of x skobochny expression (√t²*k / (1+g)) = (S + 15) / f. Then it is possible to continue simplifications by means of similar substitutions or at once to express required size: k = ((1+g) * (S + 15) / f) 2/t².