抛体是指任何物体受到外力的推进而抛射出去。虽然被投扔的球可视为一种抛体，不过在武器中，抛体更常被提到。在下面可接续看到抛体运动的轨迹方程序。

除了用手投扔之外，弓箭、飞镖、长矛等类似的武器都是利用机械设备的应力来发射，这些机械设备包含投石器、弹弓、弩枪等。

另外也有用压缩气体来当作物体的动力，吹箭和气动步枪就是一例。然而大多数的枪枝都是利用化学反应来产生大量气体推进，Light gas guns就是属于此类型。在军事方面，有些抛射物的飞行是利用喷射引擎或是火箭引擎。

Projectile motion is a form of motion in which an object or particle (called a projectile) is thrown near the earth's surface, and it moves along a curved path under the action of gravity only. The only force of significance that acts on the object is gravity, which acts downward to cause a downward acceleration. Because of the object's inertia, no external horizontal force is needed to maintain the horizontal motion.