Game Development Reference
time should be in seconds (s); speed should be in meters per second (m/s); and accel‐
eration should be in meters per second squared (m/s 2 ). In the SI system, g is 9.8 m/s 2 .
In the second type of problem, the launch point is located on a lower horizontal plane
than the target. In Figure 6-2 , the launch point's y coordinate is lower than the target's
Figure 6-2. Target higher than launch point
For this type of problem, use the formulas shown in Table 6-2 . Notice that most of these
formulas are the same as those shown in Table 6-1 .
Table 6-2. Formulas—target higher than launch point
Use this formula:
(v o cos φ) t
(v o sin φ) t - (g t 2 ) / 2
v x (t)
v o cos φ
v y (t)
v o sin φ - g t
v 0 2
- 2 gtv 0 sin φ + g 2 t 2
(v o 2 sin 2 φ) / (2 g)
v o T cos φ
(2( h - b ))
(v o sin φ) / g +
Actually, the only formula that has changed is that for T , where it has been revised to
account for the difference in elevation between the target and the launch point.
In the third type of problem, the target is located on a plane lower than the launch point;
in Figure 6-3 , the target's y coordinate is lower than the launch point's y coordinate.