EarthSurfaceGravAccel
Near Earth's surface, the magnitude of the gravitational acceleration, $g$, is approximately $9.8 \, \mathrm{m/s}^2$.
EarthSurfaceGravDir
Over a sufficiently small area of Earth's surface, the direction of Earth's gravitational acceleration can be approximated as constant, and defines "down".
IndepMotions
The component of an object's velocity along an axis is not affected by a component of acceleration along a perpendicular axis.
KinEqn2_dvt
One-dimensional motion with constant acceleration is described by the equation $x_\text{2}=x_\text{1} + \frac{1}{2} (v_\text{1}+v_\text{2}) (t_\text{2}-t_\text{1})$, where $x_\text{2}$ is the position at time $t_\text{2}$, $x_\text{1}$ is the position at time $t_\text{1}$, $v_\text{2}$ is the velocity at time $t_\text{2}$, and $v_\text{1}$ is the velocity at time $t_\text{1}$.
KinEqn3_dv_plus_at^2
One-dimensional motion with constant acceleration is described by the equation $x_2=x_1 + v_1 (t_2-t_1)+\frac{1}{2} a (t_2-t_1)^2$, where $x_2$ is the position at time $t_2$, $x_1$ is the position at time $t_1$, $v_1$ is the velocity at time $t_1$, and $a$ is the acceleration.
TopOfFlight
At the highest point of an object's trajectory, the vertical component of the object's velocity is zero.
