Learning goal: to understand the basic concepts of projectile motion. projectile motion may seem rather complex at first. however, by breaking it down into components, you will find that it is really little different from the one-dimensional motions that you may already have studied. one of the most often used techniques in physics is to divide two- and three-dimensional quantities into components. for instance, in projectile motion, a particle has some initial velocity v? . in general, this velocity can point in any direction in the xyplane and can have any magnitude. to make a problem more manageable, it is common to break up such a quantity into its x component v? x and itsy component v? y. imagine that the ball on the left is given a nonzero initial velocity in the horizontal direction, while the ball on the right continues to fall with zero initial velocity. what horizontal speed vx must the ball on the left start with so that it hits the ground at the same position as the ball on the right?