[no_mind_golfer]

I've got to say... re. BerntR

That (what you said) don't make a whole lotta sense to me.

You start out good re... the centripetal acceleration stuff, but then you lose me when you say: centripetal stores energy (no) and things in the golf swing are harmonic (sinusoidal as in sin and cosine) (no) and golfers are a drag.

Whoa nelly.... Lets take a step back here.

Everyone knows that there some guys who can hit pretty darn far with club head tied to string. Who was that instructor? famous guy who's name escapes me... anyway it don't matter.

Lets forget for a moment any torque (pun not intended) the golfer might impart via push/pull between that hands and consider the "pure swinger" case (club head on string)

If at any time during the downswing we drew a free body diagram of the club head it would show only one force acting on it (for the time being forget about gravity too ok... trust me its a minor contribution). We would call that one force acting on the club head (drum roll please..... no not centrifugal.... no not centripetal.... no not tangential no not radial...) we would call that force TENSION. Furthermore if we consider the "local coordinates" of the club head (see 2/3 down the page here: http://en.wikipedia.org/wiki/Centripetal_force ) we would find TENSION has both a tangential and radial (aka centripetal) components (again...is in local coordinates Tension has both tangential and radial (orthogonal) components). The force is tension... and it has two components: tangential and radial or centripetal.

{{{ Its worth mentioning that only w^2/r of the radial component is "centripetal" ... and excess us just radial }}}}

NOW the radial or centripetal component (being, by definition, directed at the instantaneous center of rotation (not left shoulder... not hands ... but at the instantaneous center of rotation as defined solely by the path of the club head itself) is what's know as a "central force" ( http://en.wikipedia.org/wiki/Central_force ) .... (and here is where we (mostly) agree Berntr... central forces (ie radial ones) generally do not increase the angular velocity of a rotating obect and the centripetal central force NEVER does.

Said another way, the centripetal component of the tension in the rope tied to the club head (usually) does not increase the speed of the club head. Its that tangential component which increases the speed of the club head.

(But there is a caveat to this ... central forces (NOT the CENTRIPETAL variety) in general CAN pump in energy see http://www.lynnblakegolf.com/forum/n...wreply&p=59297 )

This is why when Jeff swings his ball on a string, the central pivot must trace a curvilinear path.... in order to generate a tangential component which is solely responsible for making the ball rotate, the tension force in the string must not point at center of rotation.

Anyway in the ball on a string case, we must do that because the ball has AERODYNAMIC DRAG which acts in a tangential direction which must be overcome. Were the ball already spinning in the vacuum of space , then tension need only point to the center of rotation. The club head is subject to AERODYNAMIC "DRAG" too.

Just a thought...