# Formulae and Graphs

The positions of the cars depend on the time `t`. For each car there is a rule for finding the position. The
rule is described by a **formula** in terms of `t`. Since each value of `t` will correspond to one
position of a car, the position is a **function** of the time.

If you want to describe the movement of a car on a paper (where the car cannot move) you can
think of `t` as changing along one direction and the position along another direction (by
using a Cartesian coordinatesystem). Then you can plot the movement.
Your plot is the **graph** of the function.

## Find the formula

Find the formula of the functions \(y_i=f(x_i)\) for \(i=1,2,3,4,5\) in the applet above.

Use the applet below to check your answer, turn the
`y`-axis 90° to see the graph of the function.

by Malin Christersson under a Creative Commons Attribution-Noncommercial-Share Alike 2.5 Sweden License