The sports blog "Grantland" has an
article on the physics of tennis, focusing on how different surfaces (grass, clay, and hardcourt/cement) affect play. Three physics concepts -- the coefficient of friction, angle of rebound, and coefficient of restitution (what the article refers to as "bounciness") -- are discussed, with regard to their effects on the velocity and bounce of incoming shots and players' perceptions thereof. (Discovered
here.)