[Par71]

I didn't mean that, Daryl.

The formula for kinetic energy is "one half the mass multiplied by the square of the velocity" (2-M-1). So to impart more kinetic energy to the ball you can either increase the mass or the velocity.

Velocity is clubhead speed, and I understand how that can be varied by varying the acceleration time or the release interval (2-M-2).

The mass of the clubhead (in kilograms) is obviously constant. It does not change by acceleration or by lengthening the lever. "Effective Mass" seems to imply that an accelerating clubhead or a clubhead with a longer radius acts on the ball as if it had more mass than it really has. And I assume that this is correct. I just don't understand why it is so (the laws of physics behind that).