When a baseball curves to the right (a curveball) , air is flowing faster over the right side than over the left side. at the same speed all around the baseball, but the ball curves as a result of the way the wind is blowing on the field. faster over the left side than over the right side. faster over the top than underneath.

faster over the left side than over the right side.

Explanation:

due to ball rotation, the right side is more closely matched to the speed of the air passing by as the ball progresses. This causes the air to stick more closely to the right side of the ball and that air stays with the ball surface as the spin moves it to the back of the ball and therefore leftward. As every action has an equal and opposite reaction the leftward force moving air causes the ball to experience an equal rightward force.