curve_balls_work.mp4

[00:00:04] In the 1940s the question about curveballs was "Do they actually curve or not?" Was it an optical illusion? Well photography and science have shown that curve balls really curve. We can give one explanation for the curve ball which is the ball is spinning as it moves through the air. The seams of the ball interact with the air flowing over the ball. So as the ball is rotating rapidly, the seams give some energy to the air on one side of the ball and remove some energy from the air on the other side of the ball. If we look at the airflow we find that the air is then thrown to the side as the ball spins and it acts like a little rocket motor the spinning ball throws the air to one side and the air with action and reaction throws the ball to the opposite side. Thus the spinning ball as it comes towards you at home plate, will move in the direction the front of the ball is moving as it comes towards you, throwing the air the other way. There's an explanation for the curve ball that involves the Bernoulli principle. As the air in front of the ball passes around the ball. It has to speed up, to get around the ball. On the side that's rotating with the direction of the wind. The air speeds up more. On the other side, the air speeds up less. Again the seams speed it up and slow it down. The result is as the air speeds up the pressure is reduced. It's the same thing that happens with an airplane wing. 

[00:01:40] The air flowing over the wing speeds up more than the air flowing below the wing. The pressure on top of the wing is less the airplane gets lift. The pressure on one side of the baseball is less than the pressure on the other side of the baseball. So the baseball is pushed to one side and it actually curves as it flies through the air.