Effective striking mass

I forgot to mention Prof Stanley Plagenhoff and his book, “Patterns of human motion - a cinematographic analysis” (1971).  He posed the question what is the effective striking mass involved in various sports such as golf, tennis, soccer, martial arts.

He did measurements with golf professionals. The subjects were Floyd, Jacklin, Weiskopf, Marr, Sanders, Palmer, Henning, Beard, Still and Stckton for men and Mann, Wright, Whitworth, Haynie, Whalen and Rawls for women. There are no specifics about the measurements but it is based on acquiring head velocity just before and after impact and ball departure velocity as illustrated in Fig1. and using conservation of linear momentum.

He concluded from these measurements that the men had an advantage of 84 gm in effective striking mass due to a greater grip strength. Hence here is a scientist lecturing in the field of kinesiology who supported, 42 years ago, the view of the heavy hit in golf, i.e. a golfer can effectively increase the effective striking mass of the clubhead.

Just a few years earlier , 1968, “Search  for the Perfect Swing” was published  in which a group of English scientists experimentally showed this not being correct.  Research has also shown this to be equally true for tennis and baseball. What happens at the grip end is not of any consequence during impact.

Indeed what is the effective striking mass. Fig2 shows one  aspect. In 2a) it is intuitively evident that there is a greater striking mass involved, compared to 2b).   This could be linked to the mass of the hosel. Another aspect is the rigidity of the masses involved. For the clubhead, especially for the driver one has the trampoline effect which has the effect of increasing the effective striking mass. When oblique impact angles are involved the striking mass is also affected.

This could be an interesting experiment for anyone so interested and having access to adequate instrumentation and a golf robot.

Hence to determine the effective striking mass m1 of the clubhead it is required to measure the change in speed of the clubhead, V1-V2,  during impact and the departure speed, U2, of the ball. The mass of the ball, m2, is readily ascertained. Using a robot one can control the exact spot with which the clubhead will strike the ball. A good starting point would be using a club adjusted to have zero loft to establish some reference situation for subsequent experiments.

mandrin