Kinematics, the study of motion in one and two dimensions, describes an object's position, velocity and acceleration using a compact set of equations relating those three quantities over time. Those equations work identically whether the object in question is a rocket accelerating off a launchpad, an apple falling under gravity, or a ball thrown by hand across a field, because kinematics deliberately never asks what force actually produced the motion; it only describes the motion itself, leaving the question of cause to a separate branch of mechanics entirely.
Kinematics separates the description of motion from its explanation
This separation between describing motion and explaining its cause is a deliberate simplification, not an oversight: by setting aside the question of what force is acting, kinematics can derive a small set of genuinely general equations linking position, velocity, acceleration and time that apply to any object undergoing constant acceleration, regardless of what's actually causing that acceleration. A car braking at a constant rate and a stone falling under constant gravitational acceleration obey exactly the same kinematic equations, even though a completely different force, friction in one case, gravity in the other, is doing the causing.
Extending the description to two dimensions means tracking motion along each axis independently
Once kinematics moves from one dimension to two, describing motion across a flat plane rather than along a single line, it relies on a further, genuinely useful simplification: a two-dimensional motion, a thrown ball's arc, say, can be broken down into two entirely independent one-dimensional motions, horizontal and vertical, each governed by its own separate set of the same basic kinematic equations. The horizontal motion typically proceeds at constant velocity while the vertical motion accelerates under gravity, and treating the two directions as independent, rather than trying to solve the combined motion directly, is exactly what makes two-dimensional kinematics problems mathematically tractable using the same simple equations one-dimensional motion already relies on.
What we're still unsure about
That kinematics can describe motion completely without reference to its cause, and that two-dimensional motion can be decomposed into independent horizontal and vertical components, are well established, thoroughly confirmed principles of classical mechanics. What's more genuinely a matter of pedagogical judgement is exactly when a physics course should introduce force and Newton's laws alongside kinematics versus keeping the two topics cleanly separated, since teaching motion's description before its cause has real, contested trade-offs against teaching them together from the start, and physics educators continue to use meaningfully different sequencing depending on their own judgement about what helps students build the clearest underlying intuition.
This sits inside Kinematics in One & Two Dimensions, one of eight topics in Mechanics, one of five domains in Physics, one of seventeen subjects the app can quiz you on.