In baseball, a corked bat is a specially modified baseball bat that has been filled with cork or other lighter, less dense substances to make the bat lighter. A lighter bat gives a hitter a quicker swing[1] and may improve the hitter's timing.[2] Despite popular belief that corking a bat creates a "trampoline effect" causing a batted ball to travel farther,[2] physics researchers have shown that this is not the case.[3] In Major League Baseball, modifying a bat with foreign substances and using it in play is illegal and subject to ejection and further punishment.[4]
^Russell, Daniel (2011). "What about corked bats?". Physics and Acoustics of Baseball & Softball Bats. Penn State University. Retrieved August 1, 2019. A bat which has less mass, and especially which has a lower moment of inertia, may be swung faster.