The center of percussion is a point on a body which, when struck with a force, will have
associated with it another point called the center of rotation at which there will be a zero
reaction force. You have probably experienced the result of "missing the center of percussion"
when you hit a baseball or softball with the wrong spot on the bat. The "right
place on the bat" to hit the ball is the center of percussion associated with the point that
your hands grip the bat (the center of rotation). Hitting the ball at other than the center
of percussion results in a stinging force being delivered to your hands. Hit the right spot
and you feel no force (nor pain). The center of percussion is sometimes called the "sweet
spot" on a bat, tennis racquet, or golf club. In the case of our mallet example, a center of
percussion at the head corresponds to a center of rotation near the end of the handle, and
the handle is usually contoured to encourage gripping it there.