Simple Mathematics of the Driver

This isn’t going to be a big physics thing. I don’t know enough to write it, and would you understand it if I did?

This is about phonograph records. I know, I date myself, but they illustrate the point perfectly.

If you watch a spinning phonograph record, you would note that the part near the spindle turns very slowly, and the part at the far edge races around the turntable.

That’s because they have to make one revolution in the same amount of time, but with different distances to go.

On a 33-1/3 RPM recored, a spot a half-inch away from the spindle travels at a speed of 105 inches per minute. A spot on the far edge of the record, six inches away from the spindle, travels at 1,256 inches per minute. *

O.K.? So let’s talk about golf clubs. My 7-iron is 38″ long, and my driver is 44.5″ long.

If I swing them at the same speed, the clubhead of the driver, because the driver is a longer club, should be going 17% faster than the clubhead of the 7-iron.

That’s a theoretical analysis. Here is some actual data.

Average LPGA swing speed with a 7-iron is 76 MPH. The ball carries 141 yards at that speed. You can probably hit a 7-iron that far.

That same swing, applied to a driver, becomes 94 MPH, which is roughly 24 % faster. That yields a a carry distance of 218 yards. Add some roll-out and you have yourself a pretty decent drive …

… by swinging your driver the same as you do your 7-iron!**

Where does the extra clubhead speed come from? Why not just 17% faster?

Remember that the golf swing is a dual-lever motion. The arms, swinging from the shoulders, provide the 17%. The club, swinging from the hands to the clubhead, proved the remaining 7%.

But that’s not the point. The point is that your 7-iron swing is your driver swing. Let the design of the club (longer shaft, less loft) do the work.

——

* Scientists used a phonograph record to verify Einstein’s Special Theory of Relativity. A “clock” on the edge of the record does run slower, because it is going faster, than a “clock” next to the center of the record. The difference is really, really, really small, but it’s there.

** Red typeface is the Internet equivalent of writing something on a large polo mallet and hitting you over the head with it.

2 thoughts on “Simple Mathematics of the Driver”

  1. Good point, Bob. We shouldn’t try to “smash” the driver. It’s fun to try, but not so good for consistent accuracy. We wouldn’t normally try to smash the 7-iron, so the same logic should generally apply. And did you suggest, in red, we should switch to a large polo mallet for a driver? I haven’t tried that, but will try most anything.

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