Part one may be found by scrolling below. This is written by the author of Science in Real Life

(PART 2)
Welcome back. Everyone here? Good, on we go. When we left off, we had just figured out the generalized effect that a baseball’s rotation has its trajectory. From there it’s really just a hop, skip, and a jump to the cornucopia of curves charging into the catchers’ claws. By changing which way the ball is gripped, and the angle through which the arm rotates during the throw, a pitcher can change the axis of rotation. In addition, as with many things in life, controlling the speed of rotation is all in the wrists. Pure backspin on a ball results in an upward force, stabilizing the throw into a speedy straight trajectory – a good old fashioned fastball. A rising fastball does not actually rise, of course. That would require a backspin three times as rapid as what major league pitchers can currently achieve. Instead, it plays off our intuition about falling objects. We are so accustomed to seeing objects fall at 9.81 m/s2 that a slowly falling fastball appears to rise.

The rest of the classic tools in a pitcher’s arsenal involve some kind of lateral rotation, and hence a lateral deflection relative to the trajectory of a nonspinning ball. In other words: yes, curveballs really do curve. So do sliders, screwballs, slurves, and any of the innumerable variations on that theme. Here is a handy guide to what rotation the hitter will see for the four most common pitches from a right-handed pitcher:

Every pitch has something like this, with two notable exceptions. Those exceptions look like this:

(Image Credit: Science In Real Life)

The gyroball (recently invented in Japan) walks like a fastball, talks like a fastball, but spins like a duck. I mean, a bullet. To batters expecting the limited drop of a fastball, this can come as quite a surprise. You will notice that the knuckleball there has no arrows – it is thrown without any deliberate spin. A pitcher throwing a knuckleball puts his or her fate into the hands of Papa Physics. Stray fluctuations in wind speed, air pressure, and density can have this pitch wobbling every which way over, or not over, the plate. Without extensive practice, a knuckleball might, well, strike out.