Constants and variables
Applying mathematics in studying of laws of nature and using them in technique, we meet with constants and variables . A variable is a value, which can be changed at the conditions of the considered problem; a constant cannot be changed at these conditions. The same value can be a constant for one problem and a variable for the other.
E x a m p l e . An acceleration of a gravity is a constant for the same width of Earth, but it
changes depending on a width, i.e. in other words is a variable.
Variables are marked usually by the last letters of the Latin alphabet: x, y, z, … and constants – by the first ones: a, b, c, … .