compression vs friction

February 16 2009 at 10:42 AM
SAGF Members 2003

Response to Why

I know we've had this discussion several times but I think it's been a few years.

Sorry I can't remember details about how to post quotes, hope this is readable.

But logically, compression and friction do not really relate, do they? Both are alleged to be sources of spin. But that's the only relation i can see. Friction does not increase compression and IMO also does not increase spin. Spin comes from off center compression.

P "Out of grass you are more likely to have blades of grass between the clubface and the ball. That grass acts as a lubricant and reduces the friction between the clubface and the ball and so there is less backspin."

T I have seen this speculation before, in the studies which showed smooth irons could produce as much spin as grooved clubs (remember the Ping?) and that lubricating the surface with water did not change this. So the suggestion was made but not tested that somehow it is different with grass. Uh, how much grass does it take to do that lubrication? There may be more recent studies, I haven't kept up, but long ago when we discussed this I found that theory VERY unconvincing.

P "If the ball is hit cleanly out of a fairway bunker you will get as much spin as a clean hit from the fairway and more than you'd get if grass was between the clubface and the ball."

T Is that measurement, or speculation? I believe the part about the clean hits, just am skeptical about the grass between effect.

P "For greenside bunker shots the mechanism is different because the club does not strike the ball but the sand under it. Friction between the sand flying towards the target and the bottom of the ball produces backspin and not compression of the ball against the clubface. "

T That one I could believe, I know mine don't have much spin. How do you transfer friction from the club face to a loose pile of sand and then to the ball? Think each individual grain of sand is spinning? I guess if a loose pile of sand is going past underneath the ball you'll rotate it a little.

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