Linear and Angular Speed in the Golf Swing

What is the difference between linear and angular speed or velocity and how can something moving in a circle have a linear velocity?  I know this is a point of confusion in some golf instructors minds, and I teach basic biomechanics to track and field coaches and this one stumps them too. If you have a rock on a string and you are swinging it in a circle then the string has an angular velocity in degrees/second, but the rock at the end of the string also has a linear velocity at any instant in time (instantaneous linear velocity).  Think of it as if the string were cut then the rock would fly out at a linear velocity on a tangent to the circle.  Of course the club has this type of motion during the swing (especially the downswing).  Now linear and angular velocity are related by v = r x w where v is linear velocity (in ft/sec, mph or m/s) and r is the radius of the circle (in feet or meters) and w is the angular velocity (in radian/second or degrees/second).  What this equation means is that for a given angular velocity, as we increase the radius the linear velocity will increase proportionally. Here is a video I did for the TPI website back in 2011.  I think it explains the difference between linear and angular speed.