quote:
Originally posted by infielddad:
I continue to have trouble visualizing a hitter dropping his back shoulder, hitting the ball with the bat on a slight incline, and being able to apply backspin, which is so critical in ball flight.
I have no comment on the batter's mechanics or his shoulder. However, on the issue of backspin, the path of the bat--upward or downward angle-- is of secondary importance compared to what physicists call the impact parameter. A large impact parameter simply means a more glancing collision.
The initial trajectory of the ball and the spin of the baseball are closely linked. Any pitched ball which is hit in the air--not a grounder--will have backspin, and lots of it. It's hard for most of us to visualize exactly how the impact of the bat and ball produces spin, but it is easier to predict the intial trajectory. If the head of the bat is traveling horizontally at the time of impact, and the point of tangency (the first point of contact) between the bat and the ball is below the midpoint of the ball, which also implies above the centerline of the bat, the ball will be hit above a horizontal trajectory. The lower the point of tangency on the ball, the steeper the upward angle of launch.
If the blow is glancing enough, the ball will be hit almost straight up--the familiar popup to the catcher. And the ball will have extreme backspin, because the ball will "roll" over the surface of the bat. The converse is true. In order to get topspin, the batted ball will necessarily have an initial downward direction.
If the batter can make contact at the midpoint of the ball, there would be, roughly speaking, no spin in either direction. More correctly, the bat would need to travel upwards at the same angle, say 15 degrees, that the pitch is travels downwards, and the point of contact 15 degrees below horizontal, in order to get zero spin. A horizontal swing travels downwards at 15 degrees relative to the direction of the pitch, and that swing produces backspin, and a slightly downward trajectory, if the bat contacts the ball 15 degrees down from the midpoint.
So think about a swing in which the direction of the bat is horizontal as it contacts the ball. Compare that to a swing which hits the same spot on the ball, but which is traveling downwards at 10 degrees. The downward swing will cause about 15% greater backspin, but it also will send the ball on a trajectory which is 10 degrees lower. The lower trajectory swamps the effect of additional backspin, and the batted ball will fly a shorter distance.
Want to get more backspin so you can hit the ball farther? Contact a little bit lower on the ball.