The Center of Mass of a Baseball Bat.
You can find the center of mass of a baseball bat by finding the spot to place your finger so that the bat will remain in balance.
Finding the Sweet Spot
Baseball bats have two different "sweet spots."
The Center of Percussion
The first sweet spot is named the Center of Percussion. If you swing a bat and hit a ball near the end of the bat, the bat will pivot about a point near its Center of Mass and the handle will push your hands forward. If on the other hand you hit a bat at its Center of Mass the entire bat will try to move backward without rotating pushing your hands backward. In between these two positions of the bat is the center of percussion where the forward motion of the handle exactly cancels the backward motion of the center of mass.
The Node of Vibration
The second sweet spot is the node of vibration. Hit a bat near the fat end and it will vibrate and even make a tone you can hear. Strike the bat at different points moving slowly up the bat and you will find a point where the bat does not vibrate much at all. The point where the bat does not vibrate much when you strike it is the node of vibration.
Curve Ball thrower
Throw a ball made of styrofoam with a half-tube made of cardboard and you can throw a wicjed curve ball
Scientific Explorations with Paul Doherty
11 February 2007