Example LAPP.1 : Motion and Speed
(Velocity) $s(t)= vt + s_0$ where $s$ is position of an object moving
on a path (often a straight line), $v$ is the (constant) speed (velocity) of the moving object, $t$ is the
elapsed time that the object has been in motion, and $s_0$ is the
position of the object at time $t=0$.
Example
LAPP.3 : Direct Proportions.
Two variables $v$ and $w$ are directly proportional when the ratios
between corresponding values of the variables are equal, $v:v' :: w:
w'$.Hence , $\frac vw = a \ constant$. The (non-zero)
constant is frequently denoted with the letter $c, k$, or $\alpha$. The
relation between the two variables can also be expressed with linear
functions: $v(w) = c* w$ or $w(v) = c' *v$ where $c' = 1/c$.