[EdZ]

We have two clubs, both have the same mass, both have a speed of 100 mph at impact, both are acceleating at the same rate, both are on the correct plane and correct path, both clubs are square at ball seperation, launch angle is perfect for max. distance (may have left something out but you get the idea).

But

One club has no golfer attached!

Difference?

Absolutely.

That difference is 'support', which is indeed additional mass of the player. The difference is less slowdown due to impact and therefore faster separation speed.