Answer:
the equations of motion can be separated into an equation that depends on a single variable.
Explanation:
he one-dimensional kinematics equations can be applied to two-dimensional systems because we can write the equations in such a way that each one of them depends on variables in a single dimension plus time, which, because it is a scalar, can be used in all dimensions.
A mathematical way of saying this is that the equations of motion can be separated into an equation that depends on a single variable.