In a recent article on xkcd.com, the author writes,
Throwing is hard. In order to deliver a baseball to a batter, a pitcher has to release the ball at exactly the right point in the throw. A timing error of half a millisecond in either direction is enough to cause the ball to miss the strike zone.
To put that in perspective, it takes about five milliseconds for the fastest nerve impulse to travel the length of the arm. That means that when your arm is still rotating toward the correct position, the signal to release the ball is already at your wrist. In terms of timing, this is like a drummer dropping a drumstick from the 10th story and hitting a drum on the ground on the correct beat.[/i] http://what-if.xkcd.com/44/
which is pretty interesting, so I’ve been thinking about it. I’m wondering if the arm/hand actually does anything actively to release the ball, or if all that we do is set certain geometries and tensions in the fingers that we know will cause release to occur at the right point in the throw.
If you have played with a trebuchet (a model one hopefully), you’ll find that you can control the release point with (for example) the angle of the pin that releases the sling. I wonder if the arm works in a similar way. You set a certain tension in your fingers and when that force is exceeded, the ball flies out.
But then, you can think about the release of things besides a regular ol’ fastball. What does the hand need to do to throw a curveball, or a slider, or a knuckleball? Does it have to play an active role? What about throwing an instrument with a handle, like an axe? Or maybe the hand has to take an active role in throwing some things, and not others.
What do you think?