The direction of baseballs after pitching is caused by the spin of the ball. Spin is defined as rotations around the axis of the baseball. Major League pitchers have timed the spin on their pitches at 1500 revolutions per minute, so when a baseball spins in the air, the threads on the ball cause a self-produced "air pocket" that causes changes in direction. This is known as the Magnus effect. The rotation of a baseball is defined as a vector pointing to the rotation of the axis. And the magnitude of this rotation vector is the number of revolutions per second, this is known as the angular velocity vector (Horney, A., Lowry, T., Schwenker, E., & Wray, E. (2008). New breakthrough on baseball. Electronic Proceedings of University Mathematics, 3(4)). All baseballs are affected by this spin, and the spin is what causes the change in direction. When fastballs are thrown, the spin of the ball affects the ball and causes it to travel through the air at a faster speed. It also increases the mass of air under the ball and makes the air above the ball thinner. This creates lift and is what makes the ball go faster and causes more velocity. A curveball is almost the exact opposite of a fastball. While a fastball spins and flies the pitch tight, a curveball spins in the opposite direction. The downward rotation makes the air around the field heavy at the top and lighter at the bottom; this causes the ball to drop or break. According to Mlb.com's game day app, a typical major league curveball thrown averages less than 80 mph. While the average pitch of a fastball is over 87 mph. The next data comes from the curveballs of Bronson arroyo of the Cincinnati Reds and the fastballs of Josh Beckett of the Boston Red Socks. Although the nature of the motion on a curveball is......half of the paper...of the ball. Lift is only important to the spin of the ball if it is a fastball because the ball creates its own lift. In the 1920s pitchers used several ways to cheat by adding friction to balls in illegal ways. Pitchers sometimes used pine tar, tobacco juice, or mud on baseballs to affect the grip and friction of the ball. This caused the balls to be affected even more by the spin of the ball. Pitchers would also use a lotion or file the ball to make it smoother so base balls can travel through the air faster. This was banned because it could make pitches wild and endanger the batter. Works Cited (http://www.grc.nasa.gov/WWW/k-12/airplane/ballforce.html Horney, A., Lowry, T., Schwenker, E., & Wray, E. (2008). A new twist on baseball, 3(4)).