Driver Head Weight

Club head weight (or more correctly, club head mass) is one of the key contributors to distance off the tee. The greater the mass of the club head and the great its speed, the farther the ball will go. Unfortunately, the greater the club head's mass, the slower will be its speed at impact. One can't swing a more massive (heavier) club head as fast.

The physics of the interaction between club and ball is quite well understood. At play are the laws of momentum and energy. A given player (let's say you) is capable of swinging a club with a some maximum speed. The more massive the club, the slower will be this maximum speed. The speed of the ball is a result of the mass of the club head and its speed. So, as the mass increases, so will the resulting ball speed. But, since the club head is more massive, its maximum speed is less. There is actually an optimum mass for each golfer that produces the greatest ball speed. For most golfers, that mass is about 200 grams. A physics equation that determines the resulting ball speed is:

V = U*(1+e)/(1+m/M)

where U = club head speed, m = mass of ball, M = mass of club head

e is called the coefficient of restitution which is a measure of the efficiency of the kinetic energy transfer between club and ball. e has a value between 0 and 1. A collision with e=0 would be like a club hitting a putty ball, with the ball sticking to the club (maximum loss in kinetic energy). A collision with e=1 is called a perfectly elastic collision (no loss in kinetic energy). There would be no heat or sound produced at all, so of course is completely hypothetical.

In the past 10 to 15 years, club and ball manufacturers have made great leaps in increasing the e of the collision due mainly to the hollow, metal faced drivers whose faces can "spring back" upon collision. So much so that the USGA has put in place a legal maximum which is about 0.83. Club testers have found that e decreases with increased club head speed. Tiger Woods' drives, therefore, are not as efficient as yours or mine. He makes up for this by having significantly more club head speed.