Originally Posted by boramiNYC
shuresh u got that exactly right. the centripetal force is the basis of swinging of human arm. pulling must be toward the center. determining the center is no simple matter however but fun topic for discussion.
Bhupaes confused the centripetal force with pulling to the right because he observed the tip of the hand moving to the left when the racket tip was moving to the right (due to wrist bend, etc). Later in the arc, the hand and the racket could both be moving to the right. So, focusing on one part of the arc does not provide the right picture. There needs to be a centrally directed force in any curvilinear motion, and the direction of the force changes from instant to instant.