Whipping his racquet through the air like a cesta in jai alai, Rafael Nadal produces such tremendous topspin that the ball sometimes seems to catapult off the court, creating a shot as challenging to ...

The NFL is only concerned about players taunting opponents with their celebrations. (USATSI) Twitter's been awash with debate over the not-really-proposed-since-they're-already-in-place rules ...

Circular motion, instantaneous velocity of an object moving in a circle. When demonstrating circular motion, swing the ball in a vertical path to increase visibility. When demonstrating the ...