Video narration
Why does a ball you throw move forward, yet trace a curved path as it falls? Watch the ball as one real motion, but split it in your mind. It keeps moving forward while gravity makes it speed up downward. The forward part is its horizontal velocity: with steady gravity and no air resistance, that forward speed stays constant. The downward part changes every moment because gravity accelerates the ball toward the ground. These are not two balls or separate stages. They happen simultaneously. At first it moves forward and drops a little; then it moves the same distance forward, but drops more. Join those positions, and the path bends into a parabola used to describe projectile motion. The ball is not being steered sideways. It is simply moving forward while falling. So why the curve? Because horizontal motion carries the ball onward while gravity pulls it downward at the same time.