A projectile maintains its horizontal component of velocity due to Newton's First Law of Motion, which states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Here's why this applies to projectile motion:

* Neglecting air resistance: In ideal projectile motion, we assume no air resistance. This means there is no horizontal force acting on the projectile to slow it down or speed it up.

* Constant horizontal velocity: Since there's no horizontal force, the projectile continues moving horizontally at a constant velocity. This velocity is the same as the initial horizontal velocity given to the projectile.

Important Note: In real-world scenarios, air resistance does exist. It acts as a horizontal force, slowing the projectile down and causing its horizontal velocity to decrease over time.