Center of Percussion

Have you ever felt the “sting” of a bat? It occurs when a ball makes contact with the bat but misses the bat's “sweet spot.” In this unique activity, students will determine and test the “sweet spot” of a baseball bat while investigating pendulum motion, center of mass and torque. First, students determine the bat's “sweet spot” by comparing the bat's natural pendulum swing rate to the rate of a simple string pendulum. Next, they experiment to find the center of mass of the bat and compare that to the position of the “sweet spot.” Are they the same? Finally, they confirm the “sweet spot” by allowing the bat to swing into a block using a brittle balsa stick as the pivot. If the “sweet spot” is aligned properly with the block, the bat will strike the block true. If the “sweet spot” location is wrong, the extra torque on the bat will cause a vibration that will break the balsa stick. A discrepant event your students will never forget. Instructions are provided, and replacement balsa sticks are available. Ring stand, ring-stand clamp and rod are required, but not included.