Under ordinary circumstances, we can separate the components
of a 2-D problem, creating two independent 1-D problems.
We can use the equations of motion in 1-D to solve each of those
simpler problems.
Occasionally, you may not have enough information (three different
kinematic quantities) to determine the motion of an object
in one of the dimensions; try to solve the motion in the
other dimension, because often that will provide one extra
piece of information.
