PURPOSE: To demonstrate the sweet spot. That is, to
show the center of percussion of a baseball bat.
DESCRIPTION: A bat is held in a holder by a toothpick threaded through a
hole drilled into the handle. The location of the center of percussion is marked on
the bat. The bat impacts the edge of an iron bar at various points.
When the bat strikes the metal bar below the center of percussion it will
break the toothpick and rotate out of the holder. When the bat hits above the center
of percussion it will break the toothpick and rotate out of the holder. But when the
bat strikes the bar at the center of percussion the rotational reaction is minimized and
it will not break the toothpick in the handle.
This illustrates how a ball player wants to hit the baseball to get the greatest momentum
transfer to the ball
with the least reaction force on the batter's hands and arms. A tennnis stroke works the
same way. You can
minimize "tennis elbow" by hitting the ball at the center of percussion of the
racket so that the rotational
reaction on your wrist and elbow is minimized.
EQUIPMENT: Bat in holder, iron bar, as photographed.
Updated by Jun Qi in 3/24/2000