Video narration
When you toss a ball across a room, why does it move forward and drop at the same time? It looks like one complicated motion, but the throw contains two simpler motions. Horizontally, it keeps moving across the room. Vertically, it falls. Both happen together. Gravity changes the vertical motion, making its downward speed increase. In the ideal model, its horizontal speed stays constant. So the ball is not choosing between moving forward and falling. Gravity changes its vertical motion while its sideways motion continues. Combine those motions, and the forward travel plus the changing drop creates the familiar curved, parabolic path. Projectile motion is this combined movement. This simple model ignores air resistance and wind, so a real ball may not follow a perfect curve. Why does the tossed ball go forward and down? Because gravity pulls it down while sideways motion carries it forward.