Friction & Spin

Golfers work hard to put just the right amount of backspin on their shots, something that helps the ball stop before it rolls off the green. The brief collision between the club face and the ball produces friction, which unleashes spin. "Science of Golf" is produced in partnership with the United States Golf Association and Chevron.

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DAN HICKS reporting: From the high pitch to the gentle chip, the "short game" is something that golfers strive to perfect, and it all revolves around the physics of spin.

DREW WEAVER (2007 British Amateur Champion): Around the greens, you need something that you can control the golf ball with. And so spin is that thing.

HICKS: Professional golfer Drew Weaver says that backspin is crucial in order to get the golf ball to stop close to the hole.

WEAVER: Spin is critical. You have to figure out what clubs fit you the best and what swing to make, so you impart the right type of spin, the right amount of spin on each shot.

HICKS: Backspin on the ball is important because it helps the ball stop after it lands on the green, instead of rolling forward.

MATTHEW PRINGLE (Equipment Standards, USGA): It's going to still have some of that backspin and make for a much more controllable shot that's going to stop quicker.

HICKS: These artful spin shots come about from the collision between the club face and the ball, which last less than 500 millionths of a second. As this high-speed film shot by the United States Golf Association demonstrates, the brief contact between club and ball produces friction, which unleashes the spin.

JIM HUBBELL (Equipment Standards, USGA): During impact the ball's sliding up the face, the force of friction acts to oppose that. And that opposing frictional force is what's actually imparting spin on the ball.

HICKS: Often times, getting enough friction can be difficult due to obstructions between the clubface and the ball, primarily grass.

PRINGLE: If you're ball is nestled down there, when you hit the ball, you're definitely going to hit the grass before you hit the ball and you're going to end up with a sandwich of grass between the ball and the clubface.

HICKS: To help get the grass out of the way, clubfaces are designed with distinct score lines, or grooves.

PRINGLE: Clubfaces and certainly in irons and fairway woods and even drivers are almost always typified by having these lines in them and we call them score lines or grooves.

HICKS: Much like treads on a tire, the grooves on a clubface allow for grass, made mostly of fibers and water, to be forced away from the surface of the clubface. This provides for a cleaner contact with the ball in order to get the friction needed to impart proper spin.

PRINGLE: All that soup of fibers and water wants to go somewhere and by having grooves it gives that place that mixture, that juice, a place to go and so then the ball can have reasonably good contact with the face and get some friction and give it some spin.

HICKS: Through high-speed film, it is easy to see the efficiency of the grooves as they push away water during an impact with a ball.

PRINGLE: What happens is it channels, it rushes down into the grooves and sprays out from underneath the golf ball and when you look at a nice high speed video of that, you can see the water literally squirting out of those grooves at a tremendous rate.

HICKS: If the clubface were smooth, the grass would have nowhere to go and the amount of friction against the ball would be greatly decreased, and the spin imparted on the ball would be a lot less.

HUBBELL: The ball would just completely slide and wouldn't impart nearly any spin onto the ball.

HICKS: For golfers like Drew Weaver, finding the right amount of spin can mean the difference between landing safely on the green, or in the rough.

WEAVER: It's amazing how much science is involved, and the technology, kind of, when it all comes together how much better a golf shot can be.

HICKS: From backspin, to the grooves on a clubface, basic physics like friction and spin are what helps the golf ball stop on the green.

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