Like in a Projectile, why isn't there an acceleration in the horizontal direction? I've seen things like there isn't any force acting (in the horizontal direction) but for the body to move there must have been some force that caused the motion and by that force there must be some acceleration! So plz someone explain me the real deal!
The force that causes the projectile to accelerate in the horizontal direction is applied only when the projectile is released. For example let's say you are throwing the projectile across a field. The projectile is originally at rest in your hand. When you draw back your arm and throw it, that's when the force is applied, and that's when the projectile accelerates in the horizontal direction. After the projectile leaves your hand, there's no longer a horizontal force, and it ceases to accelerate in the horizontal direction.
Another way to think of this is, if there is still a force in the horizontal direction, what could be the source of that force? It's certainly not your hand - it's no longer in contact with the projectile. The only logical conclusion is that there isn't one; the only force acting on the projectile is gravity (neglecting air resistance).