Projectile
Definition
Any object thrown, launched, or dropped that moves under gravity's influence (ideally with no air resistance).
Unit: m (range)
Technical definition
A body in projectile motion follows a parabolic trajectory described by x = v₀cosθ·t and y = v₀sinθ·t − ½gt², with horizontal velocity constant and vertical motion uniformly accelerated. Range on flat ground: R = v₀²sin2θ/g.
Example
A soccer ball kicked at 20 m/s and 30° travels about 35 m before landing — the classic projectile problem.
Common confusion
Horizontal and vertical motions are independent — the ball's forward speed does not affect how long it stays airborne. That is why a dropped bullet and a horizontally fired bullet hit the ground simultaneously (in vacuum).