Effective Clubhead Mass

[Par71]

Could someone (possibly someone with a background in physics or engineering) please explain the physics behind the concept of Effective Clubhead Mass (2-M-2)?

I have looked up the term "effective mass" in my old physics books and on Wikipedia but cannot relate that to what Mr. Kelley talks about in 2-M-2.

[Daryl]

2-M-2 POWER REGULATION Clubhead Lag Pressure Point pressure (6-C) is the Power Regulator. It meters out Power by sensing Clubhead Acceleration Rate and Direction. That is:
To vary the Effective Clubhead Mass, vary
1. The Acceleration Rate (Lag Pressure 7-11)
2. The Swing Radius (length of the Primary Lever Assembly 6-B-0)

The above quote, HK explains the "Physics" behind the concept of "How to vary the Effective Clubhead Mass" of the Clubhead.
Maybe you need the "Laymans" explanation? See Below.

2-M-2 POWER REGULATION Clubhead Lag Pressure Point pressure (6-C) is the Power Regulator. It meters out Power by sensing Clubhead Acceleration Rate and Direction. That is:
To vary the Effective Clubhead Mass, vary
1. Swing Harder (Lag Pressure 7-11)
2. Use a Longer Club (length of the Primary Lever Assembly 6-B-0)

[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).

[Daryl]

He means for you to vary the effective mass by "You" putting more behind it. A car hitting something while traveling at one MPH will do more damage than a motorcycle hitting something while traveling at one MPH. Use greater "Lag Pressure". Be a "car". Be a "Freight Train". Heavy, not dainty.

To vary the effective mass of a nine iron by increasing the Lever Length, increase your pivot lag. Swing from the Feet. If you swing from the wrists, the Clubhead will slow from the impact force more than if you swing from the feet. Swinging from the wrists may produce enough Mass for Putting, but not for a 2 Iron.

[Etzwane]

I could not relate "effective mass" to a precise physics concept. As you said mass plays a role in kinetic energy (multiplied by velocity squared) but it also plays a role in momentum (mass x velocity) and acceleration (proportional to the force applied and inversely proportional to the mass). One common aspect of conservation of momentum when describing the feel of a golf swing is inertia.

In terms of feel in a golf swing, my guess is that these physics quantities are mixed: lag pressure and longer club makes you feel inertia (momentum or angular momentum conservation), increased lag pressure is about acceleration, a longer club will resist more acceleration but it you achieve the same rotation speed it will give more club head speed. More effective mass would need a more deliberate and steady action but a better resistance to deceleration through.

As to how "effective mass" related to the physics of impact, I have no idea.