Why does a knuckleball flutter? Why do belly flops hurt so much? Why would a quarterback prefer a deflated football? Here are 54 all-star experiments that demonstrate the scientific principles powering a wide variety of sports and activities--and offer insights that can help you improve your own athletic skills. How does a black belt karate chop her way through a stack of bricks? Use Popsicle sticks to understand why it's possible and learn the role...