Spinning (Backspin) Baseball in a Water Tunnel
Note how the Flow Reacts When the Dye Hits the Baseball's Seams

Many years ago, a boy named Candy Cummings invented a new way to throw a baseball. It is called a curve ball.

The ball curves down toward the ground. This pitch is very hard to hit. Candy Cummings is in the Baseball Hall of Fame.

Many people did not believe that a curve ball really curves. However, studies have proved that it does curve.

In baseball the pitcher must throw (pitch) the ball to a batter. He does not want the batter to hit the ball. He wants the batter to swing the bat and miss the ball. The pitcher may throw a "curve ball". He does this by twisting (snapping) his wrist as he throws the ball. This causes the ball to spin from top to bottom.

Does the ball really curve? Yes!

The spin helps the air pull the ball down faster than normal. This tricks the batter and makes the ball harder to hit.

There are many types of curve balls. These all depend on which way the pitcher snaps his wrist when he throws the ball.

A baseball only takes half a second to get from the pitcher to the batter. The batter has to think quickly to know where to swing the bat.

The ball spins forward. Air pressure and gravity force the ball to "curve" down or to the side. The batter doesn't know what to expect. He may swing and miss the ball. "Strike"!