Beginning Math and Physics for Game Programmers

Visualizing Velocity and Derivative

Let's start by revisiting the concept of velocity. Remember that velocity is a vector, so it has direction, and in one dimension that direction is either positive or negative. I also said that average velocity is defined as displacement divided by time. To help visualize the motion of an object, you can start by graphing position versus time on a traditional Cartesian coordinate system. Let's step through the process with a vertical 1D situation like throwing something into the air.

Suppose your game character throws a tomato into the air. You can track the tomato's height as time increases, which gives you the values shown in Table 9.1.

Table 9.1. A Tomato's Height at Various Times

t (in sec)	y (in ft)
0	6
1	90 ...